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

Timed just before his third rally Saturday, President Donald Trump released a memorandum on fracking and the oil and gas industry, which he told the western Pennsylvania crowd he signed on Marine One en route to the Butler County event.

Trump said the memo's intent is to "block any efforts to undermine energy production" in the state.

"So, in other words, if one of these maniacs come along and they say, we're going to end fracking, we're going to destroy the Commonwealth of Pennsylvania, you can say sorry about that," he said.

Trump used the memo to attack former Vice President Joe Biden over the Democratic presidential candidate's debate comment that he would "transition from the oil industry."

"If Joe Biden is elected, he will cancel our, and you know that, he's going to terminate, frankly -- a better word, terminate your energy industry and every job because they want to go to wind," Trump said. "They don't even want wind. Honestly, I don't think they want energy. Period."

Biden calls for net-zero emissions by the year 2050 in his climate policy, achieved by shifting away from fossil fuels but not completely banning them. Instead, Biden's policy would focus on developing carbon capture technology to reduce pollution and carbon outputs. Biden has called for no new fracking on federal lands, but that would not affect fracking already taking place or on private land.

The president also overstated what the memorandum would do. The Trump administration's memo only directed that government officials conduct an assessment of the "potential effects of efforts to ban or restrict" the use of "hydraulic fracturing and other innovative technologies for the use of domestic natural resources, including energy resources" within 70 days.

-ABC News' Will Steakin and Justin Gomez