This week, the presidential field grew more diverse with the entrance of Sen. Kamala Harris, D-Calif., and South Bend, Indiana, Mayor Pete Buttigieg.

Harris, who was born to an Indian mother and Jamaican father, announced her presidential campaign on "Good Morning America," and Buttigieg, who could make history as the nation's first openly gay presidential nominee of a major party, posted video about his forming an exploratory committee on Wednesday.

They join a growing and diverse field of Democratic hopefuls, a cadre that could prove too large for a single debate at the first opportunity in June. Anticipating a crowded field, Democratic National Committee chairman Tom Perez revealed in December that the DNC would set thresholds, including polling and fundraising targets, to pare down the first group of candidates, then "draw lots," should the group still be too large. However, the DNC has yet to reveal specific targets for those thresholds, but some figures, including Harris, who aides tell ABC News brought in $1.5 million in her first day as a candidate, are already clearly aiming for one of the coveted spots.

In our new weekly feature, ABC News and FiveThirtyEight are keeping tabs on the field as it develops.

Here's the weekly candidate roundup.

Jan. 18-24, 2019

Michael Bennet (D)

The Colorado senator attracted attention Thursday when he criticized fellow Sen. Ted Cruz, R-Texas. Bennet labeled Cruz's current government shutdown-related concerns "crocodile tears," and reminded Cruz of actions that led to a 2013 shutdown while Bennet's home state was dealing with flooding.

Asked on MSNBC Thursday afternoon whether he was running for president, Bennet said he was "thinking about it ... like every other person in [the Senate.]"

Joe Biden (D)

At a National Action Network Martin Luther King Jr. Day breakfast in Washington, Biden said that white Americans need to acknowledge and admit the fact that systemic racism still exists and must be rooted out.

The New York Times reported Wednesday that in a paid speech given by Biden in Michigan in October, the former vice president praised Republican Rep. Fred Upton, who then went on to defeat his Democratic opponent. The remarks were criticized by local Democrats, who saw it as a damaging error, according to the Times report. On Friday, at the U.S. Conference of Mayors, Biden defended the speech, explaining that he was proud of Upton's work on a cancer research funding bill and argued that not everything should be viewed through the lens of partisanship.

Michael Bloomberg (D)

Bloomberg spoke at a National Action Network Martin Luther King Jr. Day breakfast in Washington on Monday, during which he joked he would ask former Vice President Joe Biden, who was also in attendance, for tips on living in Washington. He added, of himself and Biden: "I know we'll both keep our eyes on the real prize, and that is electing a Democrat to the White House in 2020, and getting our country back on track."

The former New York City mayor faced criticism from Democrats this week after defending the use of stop-and-frisk policing during a speech at the U.S. Naval Academy in Annapolis, Maryland Tuesday, and labeling efforts to legalize marijuana "perhaps the stupidest thing we've ever done."

Cory Booker (D)

The New Jersey senator spoke at a South Carolina statehouse rally on Martin Luther King Jr. Day Monday after brief stops over the weekend in Louisiana and Georgia. In Georgia, Booker met with former President Jimmy Carter and the pair appeared on an Instagram Live video. “I’m very glad to have you here this morning, and I hope you come back,” Carter said to Booker. “And I hope you run for president.”

Sen. Cory Booker speaks during the Iowa Democratic Party's annual Fall Gala, Oct. 6, 2018, in Des Moines, Iowa.(Charlie Neibergall/AP) Sen. Cory Booker speaks during the Iowa Democratic Party's annual Fall Gala, Oct. 6, 2018, in Des Moines, Iowa.

Sherrod Brown (D)

On Wednesday, Brown told MSNBC that he continues to "very seriously" consider a presidential campaign. As has been the case in past interviews on the subject, the Ohio senator referred to the importance of Democrats competing in the center of the country and a focus on employment and job conditions.

"To win Ohio, to win the industrial Midwest, the heartland, and the Electoral College you've got to speak to the progressive base, to be sure, as I have my whole career, but you've got to talk to workers and live where they live," he said, later echoing the sentiment on "Late Night with Seth Meyers" where he said his party can't choose between progressives and workers, but represent both groups.

Brown kicks off his "Dignity of Work" tour in Cleveland on Wednesday, followed by a visit to Iowa Thursday.

Pete Buttigieg (D)

Buttigieg announced the formation of a presidential exploratory committee Wednesday, with the 37-year-old South Bend, Indiana mayor explaining that he felt it was time for a generational shift in the nation's leadership.

"I belong to a generation that is stepping forward right now," Buttigieg said in a video announcing the committee, "We're the generation that lived through school shootings, that served in the wars after 9/11. And we're the generation that stands to be the first to make less than our parents, unless we do something different."

Asked Wednesday by KCBS about potential concerns about his youth and experience, Buttigieg said his two terms as mayor and service in the Navy were more executive and military experience than President Donald Trump and Vice President Mike Pence.

Julian Castro (D)

Castro spent Martin Luther King Jr. Day in San Antonio, where he took part in the city's parade, marching alongside his brother Rep. Joaquin Castro, D-Texas.

An adviser to Castro told The Daily Beast that the former Housing and Urban Development secretary's campaign already formulated workplace harassment policies and that it would support unionization among its staffers, should they decide to do so.

John Delaney (D)

Delaney spent last weekend in New Hampshire at multiple meet-and-greet events and attended the Concord Women's March. After speaking with reporters and editors at the Nashua Telegraph last Friday, the newspaper's editorial board described the former Maryland congressman as "somewhat impressive."

Tulsi Gabbard (D)

In an interview with CNN Sunday, Gabbard said she did not regret her 2017 meeting with Syrian President Bashar al-Assad, arguing that it is "very important for any leader in this country to be willing to meet with others, whether they be friends or adversaries or potential adversaries if we are serious about the pursuit of peace and securing our country."

Eric Garcetti (D)

Garcetti helped facilitate negotiations in the Los Angeles teacher strike, which ended in a deal that the mayor called "a historic agreement."

Los Angeles Mayor Eric Garcetti speaks during the U.S. Conference of Mayors meeting in Washington D.C., Jan. 24, 2019.(Jose Luis Magana/AP) Los Angeles Mayor Eric Garcetti speaks during the U.S. Conference of Mayors meeting in Washington D.C., Jan. 24, 2019.

Jeff Flake (R)

At a Vanderbilt University panel, Flake criticized the Republican Party for moving away from "traditional conservatism." He also said, "The Trump base is very real, very solid, but politically it's just not large enough to carry ahead. I say that's a good thing."

Despite his differences with the president, Flake said at the event, “I hope we don’t go through an impeachment process because of what it does to a divided public."

Kirsten Gillibrand (D)

In her first week since the announcement of her presidential exploratory committee, Gillibrand visited Iowa, where she addressed the Des Moines Women's March Saturday. The New York senator addressed allegations of anti-Semitism against two of the Women's March leaders, saying that there was "no room for anti-Semitism" in the movement and that the movement is empowered when everyone lifts each other.

At additional stops across Iowa, Gillibrand explained the moderate positions dotting her past, including her former defense of the Second Amendment: "I had only really looked at guns through the lens of hunting. My mom still shoots the Thanksgiving turkey," she said, later noting that the NRA now gives her an F rating.

On Monday, Gillibrand spoke at the National Action Network's King Day Public Policy Forum in New York, invoking the Bible as she discussed "speak[ing] truth to power," in a moment that NAN's founder Al Sharpton characterized as "preaching."

Kamala Harris (D)

Harris officially announced Monday that she is running for president, telling ABC's "Good Morning America" that she feels "a sense of responsibility to stand up and fight for the best of who we are" and that she's confident in her "ability to lead" and "listen and to work on behalf of the American public." She then grabbed a bacon, egg and cheese sandwich, before heading back to Washington and answering questions from reporters at her alma mater, Howard University.

In the 24 hours following her announcement, aides to Harris told ABC News their campaign raised $1.5 million from 38,000 donors.

The California senator hits the campaign trail starting Friday in South Carolina to speak at an event held by a local chapter of her sorority. On Sunday, Harris will hold a campaign launch event in Oakland, then on Monday she'll participate in a CNN town hall in Iowa.

John Hickenlooper (D)

On Sunday, the former Colorado governor is visiting Iowa for a stop at a house party and a local brewery, one of his advisers told ABC News. On Tuesday, he told CNN that he would decide whether to run for president by March, and that he could separate himself for the field by sharing his bipartisan record.

"I'm probably one of the few, if not the only candidate who's actually been able to bring people together who were in conflict, they were feuding, and get them to put down their weapons, take the time to hear each other and then actually achieve progressive goals through their willingness to work together and create a compromise," Hickenlooper said.

Jay Inslee (D)

The Washington governor visited New Hampshire Tuesday to speak with students at Dartmouth and Saint Anselm colleges. He spent much of his time talking about climate change, an issue he claimed wasn't being highlighted by other possible presidential nominees.

"Here's an existential threat to the United States, and they do their rollouts and the words 'climate change' don't appear," he said.

Inslee also told the Associated Press that he's been emailing with the billionaire Tom Steyer, a fellow environmentalist who recently passed on a presidential run of his own, but who has not committed to supporting another candidate.

Washington Governor Jay Inslee attends a reception, May 4, 2018 in Seattle. (Mat Hayward/Getty Images, FILE) Washington Governor Jay Inslee attends a reception, May 4, 2018 in Seattle.

John Kasich (R)

Kasich repeated a position he's shared before when asked about a potential 2020 run during a question and answer session at the University of Florida Wednesday: "If I can't win, I'm not going to do it," he said.

The former Ohio governor wrote an op-ed for the Boston Globe to commemorate Martin Luther King Jr. Day. He decried the political division that led to the ongoing government shutdown and called upon Americans to take personal action to better their communities.

"Instead of sitting around worrying about what’s broken and not working in Washington, we’ve got to get off the couch and figure out what we can do by ourselves -- right here at home, where we live. Volunteer at the food bank. Engage with your schools if something needs to be fixed. Drop in on a neighbor who has no one else to listen," he wrote. "The opportunities are there, but we need to grasp them. That’s the cure for the breakdown in Washington."

John Kerry (D)

Asked during a panel at the World Economic Forum in Davos, Switzerland, if he had any message for Trump, Kerry answered that he should "resign."

Amy Klobuchar (D)

Klobuchar delivered last week's weekly Democratic address, criticizing Trump for "holding the hardworking people of America hostage by requiring them to pay ransom to reopen their government," referring to Trump's insistence on the inclusion of border wall funding in any appropriations bill to end the government shutdown.

Mitch Landrieu (D)

Landrieu spoke to MSNBC Wednesday where he discussed the government shutdown, saying, "The president is way stuck on stupid right now."

"There is no mayor in America in his right mind, or her right mind, that would ever think about shutting down the government," the former New Orleans mayor continued. "This is why the people of America are really frustrated with Washington."

Terry McAuliffe (D)

Though he didn't definitively commit to the race, McAuliffe told the New York Posts's Page Six of a presidential run: "It's not easy -- but I'm a heck of a fighter."

The Associated Press dug into McAuliffe's PAC's 2018 spending and found that it raised over $300,000 in the second half of 2018 and spent money on donations to the state Democratic parties of New Hampshire and Iowa -- expenditures that a spokesperson maintains said were not related to a presidential campaign.

"Funds from Common Good were used to support governor candidates and state parties across the country who share Governor McAuliffe's values," Carson told the AP, adding that the PAC is closing.

Jeff Merkley (D)

In an interview with the Associated Press, Merkley said he would decide on a presidential run before the end of April.

Senator Jeff Merkley speaks to reporters following leaving the Senate floor after delivering a 15 hour speech against Judge Neil Gorsuch on Capitol Hill Washington, April 5, 2017.(Aaron P. Bernstein/Reuters) Senator Jeff Merkley speaks to reporters following leaving the Senate floor after delivering a 15 hour speech against Judge Neil Gorsuch on Capitol Hill Washington, April 5, 2017.

Beto O’Rourke (D)

O'Rourke continued his tour of the American heartland, visiting Kansas and Colorado this week and blogging about it -- to some mockery -- along the way.

The New York Times reported Saturday that some Democrats were perturbed by O'Rourke's individualistic style, and his merely lukewarm embrace of fellow Texas Democrat Gina Ortiz-Jones during the midterms.

Mother Jones dug up a video of O'Rourke covering The Ramones in a onesie and a sheep mask.

Bernie Sanders (D)

Sanders spoke at a rally at South Carolina's statehouse on Martin Luther King Jr. Day and remained in the Palmetto State for three additional events on Tuesday. During a NAACP forum he said of a presidential campaign, "I'm going to look at it; I'm going to assess it."

In a GQ profile Thursday, Sanders detailed what he felt his 2016 presidential campaign was able to achieve, even without capturing the Democratic nomination. "“We have had more success in ideologically changing the party than I would have dreamed possible,” he said. “The world has changed.”

Howard Schultz (D)

Advisers to the former Starbucks CEO are probing the possibility of an independent presidential campaign, The Washington Post reported last Friday, citing two sources with knowledge of the conversations. CNN matched the story Monday, quoting a source who said Schultz is "thinking deeply about his future and how he can best serve the country."

Eric Swalwell (D)

Swalwell visited South Carolina Saturday to speak at the Greenville Women's March and a gala for the Spartanburg County Democratic Party. During the day, he told the Spartanburg Herald Journal that he is "getting close to deciding" about a presidential run and discussed the role that the state will play in deciding the Democratic nominee.

"Any presidential contender better come through Spartanburg County if they are going to be in the White House," he said. "It’s a steep mountain to climb for a Democrat in South Carolina since the state is mostly Republican.”

Elizabeth Warren (D)

Though still only in the exploratory committee phase, Warren continues to travel. She held an organizing event in New Hampshire last Friday, attended a Martin Luther King Jr. Day memorial breakfast in Boston Monday, visited Puerto Rico for a "community conversation" Tuesday, and visited South Carolina for another organizing event Wednesday. Friday, Warren stops in Las Vegas for an additional organizing event.

The Massachusetts senator was asked about the state of the presidential race in a CNN interview Tuesday, demurring when questioned whether she was "too far to the left."

"I'm out talking about the economic issues, about how government works, about what's happening to middle class families, working families, all across this country -- why the path has gotten rockier and rockier. This is what I've worked on all of my life," Warren said. "I'm delighted that there are lots of Democrats who want to talk about ideas, who want to talk about a way to build a stronger America; I believe in that."

Sen. Elizabeth Warren speaks during a New Hampshire organizing event for her 2020 presidential exploratory committee at Manchester Community College on Jan. 12, 2019 in Manchester, N.H.(Scott Eisen/Getty Images) Sen. Elizabeth Warren speaks during a New Hampshire organizing event for her 2020 presidential exploratory committee at Manchester Community College on Jan. 12, 2019 in Manchester, N.H.

Andrew Yang (D)

Yang, an entrepreneur, was interviewed by Rolling Stone this week about his under-the-radar campaign, where he explained why he was running for president.

"I was stunned when I saw the disparities between Detroit and San Francisco or Cleveland and Manhattan. You feel like you’re traveling across dimensions and decades and not just a couple of time zones," he said. "None of our political leaders are willing to acknowledge the elephant in the room that is tearing our communities apart, in the form of technological change."

He additionally outlined a key component of his platform: a universal basic income of $1,000 per month for all Americans 18 and older, which would be funded by a value-added tax, explaining: "If you have a town in Missouri with 50,000 adults and they’re all getting $1,000 a month, that’s another $50 million in purchasing power that comes right into that town’s local economy — into car repairs, tutoring or food for your kids, the occasional night out, home repairs. And that money ends up circulating all through that town."