Taking questions from reporters ahead of a rally in Prescott, Arizona, Trump referred to his exchanges with the press as “debate prep” and did not indicate he was doing any other preparation -- while Biden has hunkered down to get ready for their final matchup on Thursday.

"What am I doing to prepare? I'm doing this," Trump said. "I've done -- I’ve done very well in debates and you know, you do what you do. You just do what you do. The last debate I had two on one. I usually have two on one at least. And I did well in the last debate and we did well with Savannah Guthrie based on reports, but all you can do is look, you know, you go around. We do interviews with you. This is like -- I call this debate prep."

The president also told reporters he'd be fine with authorizing his doctors to release confirmation that he's been tested for COVID-19 before this week's debate in Nashville, following Biden calling it a matter of "decency" at an ABC News Town Hall last week.

"Sure, I would have no problem with it. I’m -- not only am I free -- positive or whatever, what would you call it. I'm totally free, right? Not only am I free. I'm immune, they say," he said.

Trump campaign manager Bill Stepien tweeted that he sent a letter to the bipartisan Commission on Presidential Debates demanding the third presidential debate be focused on foreign policy and also, as the campaign did on a call earlier, railed at any rule changes, including “granting an unnamed person the ability to shut off a candidates microphone.”

"The commission's pro-Biden antics have turned the entire debate season into a fiasco," Stepien said in the letter.

The letter makes no mention of the president potentially skipping the third debate if Trump's demands are not met.

The commission said last week it was looking at changes, but finals plans have yet to be announced.

Reacting to the Trump campaign’s letter to the debate commission, the Biden campaign emphasized that the decision to let moderators choose the topics was agreed upon months ago."The campaigns and the Commission agreed months ago that the debate moderator would choose the topics. The Trump campaign is lying about that now because Donald Trump is afraid to face more questions about his disastrous COVID response," Biden’s national press secretary TJ Ducklo said in a statement. "As usual, the president is more concerned with the rules of a debate than he is getting a nation in crisis the help it needs."

--ABC News' Will Steakin and Jordyn Phelps

As early voting kicks off in Florida, Harris hosted a drive-in rally in Orlando to encourage supporters in the state to get their ballots in early.

“You will be the first to put our country back on the right track,” Harris told the crowd of Floridians.

Roughly 90 cars were parked with supporters waving Biden-Harris signs and honking their horns when Harris danced out to take the stage.

During the event, she largely stuck to the campaign message of outlining Trump’s failures on the pandemic and also called him “loco” for what she called his “obsession” with ending Obama-era policies.

“He knew it was airborne. But what did he do?  He kept that information to himself. I call it a cover up,” Harris said.

“Donald Trump has this weird obsession with trying to get rid of whatever Barack Obama and Joe Biden created. Have you noticed that? It’s this weird obsession, right? Loco,” she said later on.

It’s the California senator’s first trip back on the road after cancelling trips through the weekend when two people who traveled with her tested positive for COVID-19. Harris continues to test negative, according to her campaign.

Harris next heads to Jacksonville for a voter mobilization event in the late afternoon.

-ABC News’ Beatrice Peterson

Trump, during an all-staff campaign call, attacked Dr. Anthony Fauci, the nation’s leading infectious disease expert on the president’s own coronavirus task force, as a "disaster" while also dismissing the still surging pandemic, claiming Americans are "over COVID" as U.S. deaths near 220,000.

"People are tired of COVID. Yep, there's gonna be spikes, there's gonna be no spikes, there's gonna be vaccines -- with or without vaccines, people are tired of COVID," the president said on the call, using large attendance at his recent rallies as an example. "People are saying whatever, just leave us alone."

"People are tired of hearing Fauci and all these idiots -- these, these people, these people that have gotten it wrong," Trump said. "Fauci, he's a nice guy. He's been here for 500 years ... Every time he goes on television, there’s always a bomb, but there’s a bigger bomb if you fire him. But Fauci's a disaster -- I mean this guy, if I listened to him we'd have 500,000 deaths."

Trump's attacks come after Fauci told CBS News program "60 Minutes" in an interview that aired Sunday night he was not surprised the president contracted COVID-19.

"Absolutely not. I was worried that he was going to get sick when I saw him in a completely precarious situation of crowded, no separation between people, and almost nobody wearing a mask," Fauci said. "When I saw that on TV, I said, 'Oh, my goodness. Nothing good can come outta that, that's gotta be a problem.' And then sure enough, it turned out to be a superspreader event."

It also comes as Trump trails Biden in nationwide polls, in part, due to his handling of the coronavirus pandemic.

-ABC News' Will Steakin

Vice President Mike Pence is getting set to ramp up his campaign schedule in the final days of the 2020 election with scheduled visits to Maine, New Hampshire, Ohio, Michigan, Indiana, Pennsylvania and Florida this week.

On a press call this morning, the vice president’s Chief of Staff, Marc Short, said Pence will maintain “a very aggressive schedule,” maintaining at least six days on the road with at least two rallies a day this week and they may do up to three rallies a day in the closing week.

Asked by ABC News if he will eventually link up with Trump for joint rallies, Short said that the campaign feels that "there’s a stronger benefit to them being in different markets," but that in the final days they could be doing more together.

“I think in the closing days, you will see them end up joining travel trips, and we actually do plan to do some of that a little bit beginning next week.”

Short added that the public could see them together as early as Monday during a trip to Pennsylvania and “certainly” in the “last couple of days.”

-ABC News' Justin Gomez

Early voting has begun in Florida, a state key to a Trump or Biden victory.

Of the state's 67 counties, 52 are opening their polling sites to an electorate eager to determine the outcome of one of the nation's most critical battlegrounds.

Democratic vice-presidential candidate Sen. Kamala Harris is slated to attend a drive-in rally in Orlando mid-morning and a voter mobilization event in Jacksonville in late afternoon.

As of Sunday, a staggering 2.5 million Floridians had already cast their ballots by mail -- only 200,000 shy of 2016's entire vote-by-mail total. Most polls in the state still show a tight contest between Trump and Biden.

With every state having some form of voting now underway, an unprecedented 28,117,692 voters have already voted and at least 82,013,225 ballots have been requested in early voting states, according to the United States Elections Project, spearheaded by University of Florida's political expert Michael McDonald.