In a telling sign of concern in Trump circles over slipping support among seniors, Trump held a rally this afternoon at The Villages, a sprawling mecca for retirees in a conservative pocket of central Florida -- a state he narrowly won in 2016 but is key to a 2020 victory.

"Eleven days from now, we're going to win the state of Florida. We're going to win four more years in the White House. I think Joe Biden proved last night that he's not capable of being president of the United States," Trump said, slamming Biden for painting a bleak picture of the pandemic at the final debate.

"Last night he said America is entering a dark winter. Isn't that really inspirational?" Trump continued. "He's trying to scare people basically. ... But we're not entering a dark winter. We're entering the final turn and approaching the light at the end of the tunnel."

Trump claimed that the virus is "rounding the corner beautifully" -- just one day after the U.S. set a single-day record for new coronavirus cases.

The president also teased that he'll be voting in person on Saturday in West Palm Beach. Though the president has voted via an absentee ballot in the past, he told the crowd of supporters he prefers to vote in person.

"I'm old fashioned, I guess. I like to get in line. And if I have to stand there for two hours -- maybe they'll move you up a little bit -- but I like to vote," Trump said. "Get out and vote."

Sen. Kamala Harris, D-Calif., met with students of Historically Black colleges and universities, or HBCUs, and participated in a panel discussion focused on Black men this afternoon in Atlanta at The Gathering Spot, a black-owned social club and co-working space that caters to young Black professionals.

Harris first met with HBCU students, including many from the Atlanta University Center, a consortium of Black colleges in the city. Harris, herself a graduate of an HBCU -- Howard University  -- gave brief remarks about the value of an HBCU education.

"It's about being in an environment where every message you receive challenges you to be great, because it knows your greatness. It's not something you have to prove," Harris said.

Harris made an appeal to students to get out the vote for the Biden-Harris ticket, promising a multimillion-dollar investment in HBCUs and talking about the history of suppressing the Black vote.

"We need to vote to honor the ancestors, people like the late great John Lewis, right?" she said. "There's a reason to vote, which is that there's so much at stake in the outcome of this election.”

Harris then moved to another part of the building for a panel discussion focused on Black men in which she touted aspects of Biden’s Build Back Better plan intended to support Black communities, including increasing the minimum wage and low-interest loans for minority-owned small businesses.

-ABC News' Averi Harper

In afternoon remarks on COVID-19 and the economy, Biden slammed Trump for what he called his mishandling of the coronavirus pandemic and predicted a “dark winter ahead” as the virus resurges in parts of the country.

“My fellow Americans, last night, we saw the president of the United States lie to the American people, and repeatedly lie, about the state of this pandemic,” Biden began, reading from a teleprompter for the speech. “As I told him last night, we're not learning to live with it, we're learning to die with it.”

Biden then laid out his plan to beat COVID-19 which includes, he said, enacting a national testing strategy, asking Congress for another relief bill to sign by the end of January, building a national core of contact tracers and appointing a supply commander to ensure the U.S. can manufacture critical supplies at home.

He also emphasized universal masking saying he would ask every governor to mandate mask wearing in their states and turn to local officials if they refused, along with making mask-wearing a mandatory practice  in federal buildings and on interstate transportation.

The president departed the White House South Lawn this afternoon for the battleground of Florida, a state he narrowly won in 2016, to court the senior vote first with a rally in The Villages, a sprawling mecca for retirees in a conservative pocket of central Florida.

Underpinning Trump's success in 2016 was, in part, an army of seniors that made up a large slice of the electorate and backed him by 7 percentage points over Hillary Clinton, according to national exit poll data. Older voters are among the most likely to vote and have sided with Republican nominees in every presidential election since 2004, reinforcing Trump four years ago and helping tilt key battleground states in his favor.

But this cycle, Biden is cutting into Trump's coalition, making significant gains with older voters across the U.S., particularly in must-win states for Trump. A recent ABC News/Washington Post poll found the two men running even among likely voters 65 and older nationally.

Trump is leading Biden by 8 points among likely voters over 65 in Florida, according to a recent ABC News/Washington Post poll -- a margin slashed by roughly half compared with 2016 when he carried this demographic by 17 points in the state.

Sources told ABC News Trump campaign aides have grown weary of the president's declining support among older Americans, a group they know is critical to his reelection chances.

-ABC News’ Kendall Karson and Will Steakin