Former President Barack Obama and Vice President Joe Biden are campaigning in Detroit and Flint, Michigan, Saturday in their first in-person appearance together on the 2020 campaign trail.

At the first event in Flint, Obama removed his “VOTE” mask to tell the drive-in crowd, “this Tuesday, everything is on the line.”

“Our jobs are on the line, our health care is on the line,” Obama said.

Obama bashed President Trump's response to the pandemic, saying, "If Trump were focused on COVID from the beginning, cases wouldn't be reaching new record highs."

"Trump cares about feeding his ego," the former president said.

"Joe's not going to call scientists idiots," Obama said. "He's not going to host super-spreader events."

"Tweeting at the TV doesn't fix things," Obama said, but "Biden has concrete plans."

"Joe's plan will guarantee paid sick leave for workers and parents affected by the pandemic. He'll make sure the small businesses in every community ... can reopen safely," he said.

Biden then joined Obama, telling the crowd, "It's time for Donald Trump to pack his bags and go home. We're done with the chaos ... the failure, the refusal to take any responsibility."

"Imagine where we'd be if we had a president who wore a mask instead of mocking it," Biden said.

Both Detroit and Flint are Democratic strongholds. But in 2016, declines among some of the Democrats’ core constituencies helped Trump win Michigan by under 11,000 votes.

Hillary Clinton won both Wayne and Genesee counties, home to Detroit and Flint, but her margins were significantly less than Obama in 2012.

-ABC News' Kendall Karson

First Lady Melania Trump made a campaign visit to Wisconsin Saturday, stressing that the pandemic “is not a partisan issue” and claiming “the Democrats want to project feelings of fear and doubt, purely for political reasons."

As the U.S. reaches its highest number of daily coronavirus cases, the first lady said, “We have made great progress in our fight against COVID-19… When COVID-19 invaded our country, we first had to learn what it was, how it spreads and how to prevent it.”

“Joe Biden said this will be a dark winter … his solution is to move backwards and to shut things down,” she said. “When my husband talks about the future, it is filled with continued possibility and forward thinking.”

Vice President Mike Pence jogged to the stage for his first rally of the day in Elm City, North Carolina, where he asked supporters to repeat the 2016 outcome and vote to reelect President Donald Trump.

Pence wore a mask before and after his remarks, only taking it off to speak. There were a few hundred supporters in attendance, but the majority were not wearing any face masks and were not social distancing.

Pence said that a COVID-19 vaccine is “just a short time away” and that nurses and doctors would have the supplies needed to continue treating patients as cases rise across the country.

Although Trump said the U.S. is "rounding the turn" Saturday, Pence admitted, "we continue to contend with this pandemic, we see cases rising in communities around the country."

“We are just a short time away, before the end of this year, of having the first safe coronavirus vaccine, and tens of millions of doses for the American people," Pence said. "We’re gonna continue to move heaven and Earth to make sure that our doctors and nurses have all the supplies and resources they need."

-ABC News' Justin Gomez

When vice presidential candidate Sen. Kamala Harris spoke to supporters in Miami on Saturday, she was interrupted by a male protester who shouted pro-Trump and anti-Biden slogans.

Biden supporters tried to intervene by putting Biden signs in the protester's face. The protester was escorted out by security.

Amid the disruption, Harris urged those in the audience not to be distracted.

“We're not gonna be distracted by what's at hand," Harris said, as the crowd cheered. "We're not gonna be distracted by the stakes.... We know what we have to do."

"You gotta ask, why are these powerful people trying to make it so difficult for us to vote?" she said.

Harris also has stops in Fort Lauderdale and Lake Worth, Florida, Saturday.

-ABC News' Averi Harper

For the second time Saturday, Joe Biden and Barack Obama held a drive-in rally in Michigan -- this time in Detroit -- and delivered a freewheeling event for an eager crowd that defied the campaign's calls for social distancing as they stood shoulder to shoulder near the stage. The event also featured audio problems during Obama's speech, but he took it in stride, joking with the crowd as it was fixed.

Biden was asked by a man in the crowd about the reunification of the 545 kids who were separated from their parents at the border. For the first time on camera, Biden said he'd set up a special commission to reunify the families if elected on "day one."

"The gentleman says, 'What about the 545 kids who were kidnapped?' That’s why I announced, immediately on day one, I’m setting up a special commission," he said. "We're gonna find those kids, we’re gonna unite them with their parents, we're gonna make sure their parents are together. What a total -- what a total embarrassment."

Obama again cast the 2020 race as the most important election "of our lifetimes," including his two previous successful runs for the White House.

"Three days, Detroit. Three days. Three days until the most important election of our lifetimes and that includes mine, which was pretty important," Obama said. "This Tuesday, everything is on the line. Our jobs are on the line. Health care is on the line. Whether we get this pandemic under control is on the line and the good news is on Tuesday, you can choose change. You can elect Joe Biden, you can elect Kamala Harris, you can choose a better America."

The event featured very little social distancing, the direct opposite of most Biden rallies, with a good portion of the crowd standing near the stage.

The campaign made at least a half dozen announcements asking people to return to their cars, but few obeyed, and no one stood 6 feet apart, crowding the press who were not penned off.

-ABC News' Molly Nagle, Johnny Verhovek and Beatrice Peterson