The field of candidates was large -- even as some candidates dropped out, more seemed to throw their hats in the ring. In November, for example, two people who had earlier ruled out 2020 runs launched presidential campaigns.
Following Super Tuesday, the Democrats still in the running were former Vice President Joe Biden, Rep. Tulsi Gabbard, D-Hawaii, and Sen. Bernie Sanders, I-Vt. Gabbard suspended her campaign on March 19 and in April, Sanders suspended his campaign amid the novel coronavirus pandemic that roiled the 2020 election cycle.
Three Republican challengers also declared their intention to run, even as some state party officials were canceling their nominating contests. All three have since suspended their runs in the Republican primary.
Here's who is running:
Former Vice President Joe Biden
The former vice president and senator from Delaware announced his bid April 25 in an online video.
In the video, he denounced the white supremacists who marched on Charlottesville in 2017 and Trump's response, calling it a "defining moment for this nation in the last few years."
"We are in a battle for the soul of this nation," Biden said in the video.
Biden entered the race with the kind of name recognition that made him a de facto front-runner. But he's also faced questions about accusations from women about unwanted touching, money, messaging, age, identity and ideology in a political environment vastly different from the one he began his career in decades ago.
President Donald Trump
On the same day he assumed the office of the presidency in 2017, Trump filed preliminary paperwork with the Federal Election Committee (FEC) to qualify as a presidential candidate for 2020.
Trump's re-election campaign announced in early April that it raised more than $30 million in the first quarter of 2019, a total that outpaces all of his Democratic rivals and indicates he will be well-resourced in his bid for a second term in the Oval Office.
"Our prodigious fundraising is further proof of President Trump's clear record of accomplishment on behalf of the American people," wrote Brad Parscale, campaign manager for Trump's re-election campaign.
The following candidates have dropped out of the 2020 election:
Sen. Michael Bennet, D-Colo.
The senior senator from Colorado announced his presidential bid during a May 2 appearance on CBS This Morning, just weeks after a successful prostate cancer operation.
Bennet said his ability to win over Republican constituents and colleagues, and his "broad" experience in the public and private sectors, distinguish him in a crowded Democratic field.
After the polls closed in New Hampshire, he announced he was ending his bid for the White House, but teased that he may be back.
"Tonight is not going to be our night, but let me say this to New Hampshire, you may see me once again," Bennet said.
Former New York City Mayor Michael Bloomberg
Former New York City Mayor Michael Bloomberg officially entered the Democratic primary in November, launching an unconventional pursuit of the party’s presidential nomination after years of flirting with a bid for the nation's highest office.
"I offer myself as a doer and a problem solver -- not a talker. And as someone who is ready to take on the tough fights – and win," Bloomberg said in a statement on his website. "Defeating Trump -- and rebuilding America -- is the most urgent and important fight of our lives. And I’m going all in."
By Super Tuesday, it was clear that Bloomberg's efforts to target the 15 contests in play in lieu of traditional campaigning methods of hitting the early voting states simply did not pay off in terms of netting the bulk of pledged delegates or the popular vote. His campaign was shaken by Biden's resurgence after an overwhelming victory in South Carolina that led to other moderate candidates dropping out of the race and endorsing him.
"Three months ago, I entered the race for President to defeat Donald Trump. Today, I am leaving the race for the same reason: to defeat Donald Trump -- because it is clear to me that staying in would make achieving that goal more difficult," he wrote in a letter to supporters. "I've always believed that defeating Donald Trump starts with uniting behind the candidate with the best shot to do it. After yesterday's vote, it is clear that candidate is my friend and a great American, Joe Biden."
Sen. Cory Booker, D-N.J.
Booker campaigned on a message of unity and collective action, promising to bring Democrats and Republicans together like he has on issues such as criminal justice reform during his time in the Senate.
He suspended his campaign on Jan. 13 - a day before the seventh Democratic debate, which he did not qualify to participate in due to a lack of qualifying polls towards Democratic National Committee polling thresholds, according to ABC News' analysis. It was also a few weeks before the Iowa caucuses where he was expected to finish outside the top tier of candidates -- based on recent polling.
Montana Gov. Steve Bullock
Montana Gov. Steve Bullock is most notably known for winning in 2016 as a Democrat in a state that helped elect Trump.
"As a Democratic governor in a state Trump won by 20 points, I don't have the luxury of only talking to people who agree with me," Bullock said in his May announcement video. "I go all across our state's 147 thousand square miles and look for common ground to get things done."
He campaigned for 202 days, but failed to gain traction at the national level, did not reach 2% in any of the Democratic National Committee qualifying polls and only made one debate stage. He suspended his campaign on Dec. 2 and said in a statement, "While there were many obstacles we could not have anticipated when entering this race, it has become clear that in this moment, I won’t be able to break through to the top tier of this still-crowded field of candidates."
Former South Bend, Indiana, Mayor Pete Buttigieg
Buttigieg first made a national name for himself with a bid for Democratic National Committee chair in 2017. He was the youngest candidate in the 2020 race, and could have become the first gay man to be elected president.
While he trailed many of his opponents in name recognition early on, Buttigieg argued that he could represent a generational shift in government, and speaks frequently of issues that will affect younger Americans, such as tax reform, gun control and climate change.
"I get the audacity of somebody like me talking about running for this office, but frankly it's a leap for anybody," Buttigieg said on ABC's "This Week" in February. "And yet all of the people who had that job have been mortals who just bring their experience to the table. My experience is that of guiding a city through transformation, and I think a mayor at any level has the kind of executive frontline government experience and, by the way, problem-solving experience that we need more in Washington right now."
Late on March 1, following the South Carolina primary and ahead of Super Tuesday, he said "the path has narrowed to a close" and announced that he was suspending his 2020 presidential campaign.
Former Secretary of Housing and Urban Development Julian Castro
"I'm running for president because it's time for new leadership, because it's time for new energy, and it's time for a new commitment to make sure that the opportunities I've had are available for every American," he said.
In 2016, Castro was vetted by Hillary Clinton to be her running mate, but the spot ultimately went to Sen. Tim Kaine, D-Va., This year, he said he is eager to restore the style of leadership the nation had under Obama.
Castro dropped out of the race on Jan. 2 after falling short in polling, fundraising, and eventually failing to make the November and December debate stages.
New York City Mayor Bill de Blasio
De Blasio, who is in his second term, joined a crowded field of nearly two dozen Democrats in the race for the White House. The central theme of de Blasio's campaign was "working people first."
On Sept. 20, de Blasio announced he was dropping out of the race. The mayor struggled in the polls and did not qualify for the third round of Democratic primary debates, hosted by ABC News.
"Getting out there, being able to hear people's concerns, address them with new ideas has been an extraordinary experience," he said on MSNBC's "Morning Joe." "But I have to tell you, at the same time I feel like I've contributed all I can to this primary election and it's clearly not my time. So I'm gonna end my presidential campaign, continue my work as mayor of New York City, and I'm gonna keep speaking up for working people."
Former Rep. John Delaney, D-Md.
The Maryland congressman was only seven months into his third term when he announced his candidacy in July 2017, becoming the first member of Congress to launch a bid in the 2020 cycle.
"What the American people are really looking for is a leader to try to bring us together, not actually talk like half the country's entirely wrong about everything they believe," Delaney said on ABC's "This Week" in January 2019, adding, "One of the things I've pledged is in my first hundred days, only to do bipartisan proposals. Wouldn't it be amazing if a president looked at the American people at the inauguration and said, 'I represent every one of you, whether you voted for me or not and this is how I'm going to prove it.'"
On Jan. 31, Delaney announced he was dropping out of the race.
"This race was never about me, but about ideas and doing what’s right for our nation," he said in a statement. "The unique and data-driven ideas that our campaign generated – on how to create a functional universal health care system, price carbon, advance trade, invest in rural America, cure disease, help workers, launch negative emissions technologies, reform education, and expand national service -- are now ideas for the party and I will continue to advocate for them in my next chapter."
Rep. Tulsi Gabbard, D-Hawaii
Democrat and Iraq War veteran Gabbard announced her presidential bid in January 2019 in an appearance on CNN.
Early on in her campaign, the first American Samoan and the first Hindu member of Congress faced questions over her work in the early 2000's for an anti-gay organization run by her father and her defense of Syrian President Bashar al-Assad, with whom she controversially met in 2017.
Gabbard announced the end to her campaign March 19, following continued low placement in national polls, a weak finish during Super Tuesday and subsequent contests, and failing to meet the thresholds to participate in the most recent series of Democratic National Committee sponsored debates.
Sen. Kirsten Gillibrand, D-N.Y.
The New York Democrat formally announced her presidential run on March 17 in a video posted to her verified YouTube account. In January, she had announced that she was forming a presidential exploratory committee during an appearance on CBS' "The Late Show with Stephen Colbert."
"I'm going to run for president of the United States because, as a young mom, I'm going to fight for other people's kids as hard as I would fight for my own," she said during the interview.
On Aug. 28, Gillibrand announced she was ending her presidential campaign. In a video posted to her Twitter account, Gillibrand thanked her supporters and made a call to action to defeat Trump and secure a Democratic majority in the U.S. Senate.
"We wanted to win this race, but it's important to know when it's not your time, and to know how you can best serve your community and country," she said. "I believe I can best serve by helping to unite us to beat Donald Trump in 2020."
Former Sen. Mike Gravel, D-Alaska
Mike Gravel's unlikely bid for president was launched by two teenagers who learned about him through a podcast and encouraged the former Alaska senator to run for president in 2020.
Having failed to make the debate stage during the first two Democratic debates, Gravel's team decided to close up shop on their campaign and redirect their efforts towards a think tank. In a video posted to Twitter, he endorsed Sanders for president.
His campaign was being transitioned into a progressive think tank called the Gravel Institute.
Sen. Kamala Harris, D-Calif.
"I love my country. I love my country," she said. "This is a moment in time that I feel a sense of responsibility to stand up and fight for the best of who we are."
If Harris were to win the 2020 presidential election, she would have become the first woman and woman of color to ascend to the nation's highest office. However, she announced the suspension of her presidential bid in December.
"My campaign for president simply doesn’t have the financial resources we need to continue," she said in an email statement to her supporters. "I’m not a billionaire. I can’t fund my own campaign. And as the campaign has gone on, it’s become harder and harder to raise the money we need to compete."
Former Colorado Gov. John Hickenlooper
Hickenlooper joined the field in early March, seeking to parlay his success in growing Colorado's economy while passing environmental regulations and gun control laws into a successful presidential campaign. In a launch video, he spoke further of healing the nation's political divisions.
"One thing I've shown I can do, again and again, is create teams of amazingly talented people and really address these issues that are the critical issues facing this country," he said on "Good Morning America."
He also announced he was suspending his campaign with a video.
"While this campaign didn't have the outcome we were hoping for, every moment has been worthwhile and I'm thankful to everyone who supported this campaign and our entire team," he said in the video posted to Twitter.
Washington Gov. Jay Inslee
The Washington governor is currently serving his second term in Olympia after more than two decades as a member of Congress, and said that while he is proud of efforts to raise the state's minimum wage and increase access to early childhood education, his presidential bid would prioritize climate change, which he labeled an "existential threat" during his launch event.
On Aug. 21, he announced on MSNBC that he was dropping out of the race.
"It's become clear that I'm not going to be carrying the ball, but we're going to make sure somebody is," he said in the interview.
Sen. Amy Klobuchar, D-Minn.
Klobuchar launched her campaign on a snowy February day in Minneapolis, laying out a platform that included a constitutional amendment to overturn the Citizen's United Supreme Court decision, signing back on to the Paris climate agreement and advocating for criminal justice reform and universal health care.
"I'm running for every parent who wants a better world for their kids," Klobuchar said at her opening rally. "I'm running for every student who wants a good education. For every senior who wants affordable prescription drugs. For every worker, farmer, dreamer, builder. For every American. I'm running for you."
The Minnesota senator was viewed favorably by some in Democratic circles for her ability to perform strongly in her home state -- part of a Midwestern region that helped Trump to victory in 2016.
However, the day before Super Tuesday, she suspended her bid, following an underdog third place finish in the New Hampshire primary and two sixth place finishes in Nevada and South Carolina -- two states with substantially more diverse electorates.
Miramar, Florida, Mayor Wayne Messam
The little-known Florida mayor joined the growing list of 2020 presidential candidates, announcing his candidacy on March 28 despite facing an uphill climb for his bid.
He announced that he was suspending his presidential campaign on Nov. 20 in a tweet.
"I am Suspending My 2020 Presidential Campaign But I’m Not Finished Yet," he posted on the morning of the fifth Democratic debate in Atlanta.
Messam is currently the chief executive of a city of 140,000 residents -- more than the population of the city Buttigieg runs in Indiana. He is known by many Floridians for playing football for Florida State University in the 1990s.
Rep. Seth Moulton, D-Mass.
Moulton, a Marine veteran who served in Iraq, is known as an outspoken critic of his own party. He was elected to the House in 2013.
During the 2018 midterms, Moulton raised more than $4 million through his Serve America PAC to support Democratic candidates running in battleground states. Before announcing his candidacy, he had already laid groundwork for his 2020 campaign, having visited Iowa, South Carolina, New Hampshire and Nevada.
On Aug. 23, Moulton dropped out of the race. He told The New York Times, "I think it's evident that this is now a three-way race between Biden, Warren and Sanders, and really it's a debate about how far the left wing party should go." He will seek re-election in the House to represent the 6th district of Massachusetts, according to The Times.
Former Rep. Beto O'Rourke, D-Texas
"Our campaign has always been about seeing clearly, speaking honestly, and acting decisively. In that spirit: I am announcing that my service to the country will not be as a candidate or as the nominee," he wrote.
He rose national prominence during his unsuccessful run against Texas Sen. Ted Cruz in 2018 and officially announced his presidential campaign in mid-March, calling it "a defining moment of truth for this country and for every single one of us."
Within days, O'Rourke's campaign announced it raised over $6.1 million in the first 24 hours following his announcement, topping Sen. Bernie Sanders' previous high-water mark of $5.9 million.
Former Massachusetts Gov. Deval Patrick
Patrick, the former two-term governor of Massachusetts and the state's first black chief executive, formally announced a bid for the Democratic presidential nomination in a sharp reversal from his 2018 decision to not pursue a run -- injecting more uncertainty into an unsettled primary less than three months before the first votes.
Following his announcement, he traveled to New Hampshire and filed paperwork to appear on the primary ballot. It was a day before the deadline to file.
While in Manchester, New Hampshire, he told ABC News' Whit Johnson, "I wouldn't be in it if I didn't think I could win it."
The day after the New Hampshire primary, he suspended his run and told his supporters in a statement that the outcome in the state wasn't enough to "create the practical wind at the campaign's back to go on to the next round of voting."
Rep. Tim Ryan, D-Ohio
The Ohio Democrat, who announced his candidacy on ABC's "The View" on April 4, billed himself as someone who could unify the progressive wings of the Democratic Party with the more middle-of-the-road working-class voters.
Ryan, a more moderate voice in the crowded field of competitors, rose to the national political stage in 2016 when he launched a failed bid to replace Rep. Nancy Pelosi, D-Calif., as House minority leader. He had previously been floated as a potential candidate in the 2014 Ohio gubernatorial election.
On Oct. 24, he posted a video to announce that he was withdrawing from the presidential campaign.
"While it didn’t work out quite the way we planned, this voice will not be stifled," Ryan said in a statement. "I will continue to advocate and fight for the working people of this country -- white, black, brown, men, women."
Sen. Bernie Sanders, I-Vt.
After a 2016 campaign that saw him amass millions of supporters even as he finished second to Hillary Clinton, Sanders entered the 2020 race in February 2019, predicting victory and pointing to the progressive ideas he had championed as an outsider during the last cycle, like "Medicare for All" and free college tuition, that have since become increasingly mainstream.
In an email to supporters announcing the launch of his campaign, Sanders further took aim at Trump, using some of the starkest language of a Democratic candidate up to that point, "You know as well as I do that we are living in a pivotal and dangerous moment in American history," he wrote. "We are running against a president who is a pathological liar, a fraud, a racist, a sexist, a xenophobe and someone who is undermining American democracy as he leads us in an authoritarian direction."
Sanders suspended his campaign on April 8, amid the coronavirus pandemic that roiled the 2020 election cycle.
"We are now some 300 delegates behind, Vice President Biden, and the path toward victory is virtually impossible, "Sanders said in a virtual address to supporters. "So while we are winning the ideological battle and while we are winning the support of so many young people and working people throughout the country, I have concluded that this battle for the Democratic nomination will not be successful. And so today, I am announcing the suspension of my campaign."
Former governor and Rep. Mark Sanford, R-S.C.
Former South Carolina governor and congressman Mark Sanford announced on Sept. 8 that he would challenge the president in the 2020 Republican primary.
"We have a storm coming that we are neither talking about nor preparing for given that we, as a country, are more financially vulnerable than we have ever been since our Nation's start and the Civil War. We are on a collision course with financial reality," he posted on Twitter, outlining his reasons for running.
Two months later, in November, he suspended his bid, telling reporters, "Based on the impossibility of trying to raise the issues I’ve been trying to raise which is debt, deficit, government spending in the midst of an impeachment. So call me a casualty of the impeachment process." He added that he felt it was impossible to get meaningful debate on anything because of partisan fighting over the impeachment inquiry process.
Sanford's tenure as South Carolina governor was rocked by scandal in 2009 after he secretly traveled to Argentina to meet with his lover, Buenos Aires resident Maria Belen Chapur. He confessed to having an extramarital affair in a news conference after his return. He finished his term as governor and was elected to Congress several years later.
Former Rep. Joe Sestak, D-Pa.
Sestak, a former Pennsylvania congressman and a retired three-star admiral in the U.S. Navy, dropped out of the race on Dec. 1. He entered the field at the onset of the first presidential debates in June, despite never qualifying for one.
"I know there is a tear in that fabric right now; but it can be repaired by someone who can lead, and therefore unite, all Americans," Sestak wrote in a Twitter post announcing the end of his candidacy.
Sestak began his career in the Navy in 1974, before becoming the highest-ranking military officer ever elected to Congress in 2007, according to his campaign website. He served in the House until 2011.
In 2016, he competed in the Democratic primary to unseat Sen. Pat Toomey in a tough battleground race but was defeated by Democratic rival Katie McGinty.
Tom Steyer, a billionaire liberal activist from California, in July became the 26th major Democratic figure to enter the 2020 race, reversing course on a statement he made months earlier saying he wouldn't run.
Steyer poured millions of his own money into electing Democrats throughout the years, and said in January that he would redouble his efforts to impeach the president instead of seeking the Democratic presidential nomination in 2020. But when he changed course, wrote in a tweet that his efforts to "hold the president accountable" were "not enough."
Hours after the polls closed in South Carolina on Feb. 29, Steyer announced he would end his presidential bid.
"I said if I didn't see a path to winning, that I'd suspend my campaign. And honestly, I can't see a path where I can win the presidency," Steyer said that night. "Meeting you and the rest of the American people is the highlight of my life."
Rep. Eric Swalwell, D-Calif.
The California congressman and vocal critic of the president, Swalwell officially launched his bid for the Democratic nomination on April 8. Swalwell, who stopped in several early-voting states during the leadup to his announcement, was rooting his campaign's agenda in the issue of gun control. Following his formal announcement, he held a town hall in Sunrise, Florida, with Marjory Stoneman Douglas High School students and families.
"I'm telling folks, keep your rifles, keep your shotguns, keep your pistols, we just want the most dangerous weapons out of the hands of the most dangerous people," Swalwell told ABC News Chief Anchor George Stephanopoulos on "Good Morning America" on April 9. "Most gun owners believe that."
On July 8, he became the first of the more than 20 Democratic nominees to drop out of the race.
"I ran for President to win and make a difference in our great country," Swalwell wrote in a news release. "I promised my family, constituents, and supporters that I would always be honest about our chances. After the first Democratic presidential debate, our polling and fundraising numbers weren't what we had hoped for, and I no longer see a path forward to the nomination."
Former Rep. Joe Walsh, R-Ill.
Conservative firebrand former Illinois Rep. Joe Walsh announced in August on ABC's "This Week" that he was launching a long-shot Republican presidential primary challenge against the president. Walsh was the second Republican to jump into the primary to challenge Trump.
When ABC News Chief Anchor George Stephanopoulos pointed out the massive uphill climb Walsh had in front of him in the primary, thanks to Trump's overwhelmingly high approval rating within the party, the controversial former congressman argued that conservatives should have an alternative to the president, saying, "I'm running because he's unfit; somebody needs to step up and there needs to be an alternative. The country is sick of this guy's tantrum -- he's a child."
On Feb. 7, three days after the Iowa caucuses, Walsh ended his long-shot bid.
"I’ve suspended my campaign because I’ve concluded that no one can beat Trump in a Republican nomination -- not me, not anyone," Walsh said in a statement. "That was crystal clear to me this week when I stood in front of 3,000 Iowa Republicans and was booed and jeered at for saying we deserve a president who is honest, decent and puts the country first. The Republican party has become a cult."
Sen. Elizabeth Warren, D-Mass.
"This is the fight of our lives," the senator said. "The fight to build an America where dreams are possible, an America that works for everyone. I am in that fight all the way."
The progressive candidate who ran against corruption and pumped out more than 50 policy proposals during her campaign, suspended her run after a lackluster finish in all four early voting states and on Super Tuesday -- where she even came up short in her home state. Her best finish was in Iowa, where she came in third.
"I will not be running for president in 2020. But I guarantee I will stay in the fight for the hard-working folks across the country who've got the short end of the stick, over and over," she told reporters at a media availability in Cambridge, Massachusetts, on March 5.
Former Massachusetts Gov. Bill Weld
Weld, a current partner at the Mintz Levin law firm and the 2016 vice presidential candidate for the Libertarian Party, said he would have been "ashamed" if he passed on running against Trump for the Republican party nomination.
Weld sent out a statement to his supporters that he was suspending his campaign on March 18, a day after ABC News projected that Trump had reached the delegate threshold and was the presumptive nominee. Weld only won a single delegate in the Iowa caucuses.
"I am intensely grateful to all the patriotic women and men who have stood with me and supported me during the past eleven months in our effort to bring better government to Washington, D.C," he wrote. "But while I am suspending my candidacy, I want to be clear that I am not suspending my commitment to the nation and to the democratic institutions that set us apart."
Author Marianne Williamson announced the launch of her campaign in Los Angeles in January after making six trips to Iowa and one to New Hampshire over the past year as she explored a bid.
Williamson is best known outside of political circles as the author of several popular self-help books and as a "spiritual friend and counselor" to Oprah Winfrey, with multiple appearances on her show and television network. She also ran to represent California's 33rd Congressional District in 2014 as an independent, finishing fourth in the open primary, after endorsements from then-Rep. Keith Ellison, former Govs. Jennifer Granholm and Jesse Ventura, and former Reps. Dennis Kucinich and Alan Grayson.
On Jan. 10, 2020 -- on the eve of early state caucuses -- Williamson suspended her campaign, saying that she didn't want her presence to hurt progressive candidates and recognizing that she would not garner enough votes to move forward.
"These are not times to despair; they are simply times to rise up," she said in a farewell to her supporters. "Things are changing swiftly and dramatically in this country, and I have faith that something is awakening among us. A politics of conscience is still yet possible. And yes ... love will prevail."
Yang, an entrepreneur, was running a presidential campaign most commonly noted for its support of universal basic income -- a pledge to provide all Americans 18 and older with $1,000 per month. He spoke frequently about income inequality and the economic transformation that has enriched certain parts of the country while disproportionately harming regions that have failed to keep pace.
Yang was widely regarded as a breakthrough candidate who surpassed the expectation of many as he outlasted sitting senators, former governors and other lifelong politicians as political newcomer. Yang has never held an elected position, yet generated a strong following that carried him through multiple Democratic debates.
Shortly after the polls closed in New Hampshire, Yang announced he was ending his bid.
"While there is great work left to be done -- you know I am the MATH guy -- it is clear tonight from the numbers that we are not going to win this race," he said.