President Trump had an eye on Joe Biden and Barack Obama today, telling the crowd in Montoursville, Pennsylvania, at his fourth rally of the day he watched their events and that they "draw flies." Of course, the Biden campaign uses limitations due to the ongoing COVID-19 pandemic, which the Trump campaign does not.

Trump falsely suggested that the scientists advising Biden have called for "slowing down" a coronavirus vaccine for political gain and erroneously claimed that it was Biden and Kamala Harris who don’t believe in science, when it's been Trump himself often dismissing scientific evidence that the pandemic is still surging.

He also falsely claimed that Biden and Harris were trying to "discourage" people from taking the vaccine. Both Harris and Biden have said that they would be vaccinated if it was recommended by health professions, but not if it was only suggested by Trump.

"Our opponents do not believe in science. They want unlimited power over you and your family. They got to open it up. The so-called experts advising Joe Biden have called for slowing down the vaccine," Trump claimed without evidence. "Can you believe this? Now, if it weren't in my opinion so political, they just didn’t want to have it come out before the election. But everybody knows it's right there, and we're ready to go, but it became a big political thing and they were actually trying to discourage people from taking it. That’s so bad and so stupid and so dangerous."

A vaccine is not yet ready, though health officials have said the Food and Drug Administration may grant emergency use authorization to one by the end of the year. High-risk individuals and health care workers would likely be the first vaccinated, with all Americans possibly receiving the vaccine by June 2021.

At one point, seemingly oblivious to the optics, Trump started pointing out people in the packed, mostly maskless crowd who don't have as good an immune system as young people as he made a case for reopening schools.

"They have great immune systems; stronger than you or you or you. That guy, definitely stronger than him," Trump said, pointing out members of the crowd. "And they have got to go back to school, OK? They got to go back to school."

-ABC News' Will Steakin and Justin Gomez

Kenosha, Wisconsin, is under a microscope for many reasons: It went to Trump by just over 200 votes in 2016 after delivering Obama to victory twice in 2008 and 2012, and it became a flashpoint for racial reckoning this summer when a police officer shot unarmed Jacob Blake seven times, sparking protests in the city and around the country.

As Nov. 3 nears, both Democrats and Republicans say those reasons are why enthusiasm is high: people are keenly aware of the impact of their vote, and the protests hardened voters' stances on racial injustice or law enforcement.

On enthusiasm, Kenosha County Republican Chair Erin Decker said, "This year is off the charts."

"A lot of people in 2016 were voting against Hillary [Clinton], because they did not like Hillary, and they liked Trump, but they really disliked Hillary, and now it's, I don't know a single person that's voting against Biden, they're all voting for Trump."

Meanwhile, Lori Hawkins, Kenosha County Democratic chair, said she's seeing high voter engagement, too.

"Joe Biden is popular, you know, there's people who had other opinions of who they wanted to see on that ticket early on, but he's done a really good job of letting the voter know who he is."

The protests and ensuing violence in Kenosha deepened that engagement, both Decker and Hawkins said.

"I think suburban women, you know, they're concerned about safety for their children, and their families. They're not in favor of the violence that has happened in Kenosha," Hawkins said, reflecting on how the protests forced law enforcement over racial injustice to the top of the ballot. "So I think when it comes down to it, they're, they're more concerned about their family safety, over, pretty much anything."

-ABC News' Cheyenne Haslett

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

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