JOHNSTOWN, Pa. (AP) — With Election Day just three weeks away, President Donald Trump and Democratic challenger Joe Biden concentrated Tuesday on battleground states both see as critical to clinching an Electoral College victory, tailoring their travel to best motivate voters who could cast potentially decisive ballots.

Biden went to Florida to court seniors, looking to deliver a knockout blow in a state Trump needs to win while trying to woo a group whose support for the president has slipped. And Trump visited Pennsylvania, arguably the most important state on the electoral map, unleashing fierce attacks on Biden's fitness for office in his opponent's backyard.

“He’s shot, folks. I hate to tell you, he’s shot," Trump told a big rally crowd in Johnstown, saying there was extra pressure on him to win because Biden was the worst presidential candidate of all time. “Can you imagine if you lose to a guy like this? It's unbelievable."

In his second rally since contracting the coronavirus, Trump spoke for more than an hour to a crowd of thousands packed in tightly and mostly maskless. Like the night before in Florida, Trump seemed healthy, and his rhetoric on the pandemic — including the dubious claim that it was mostly a thing of the past — changed little despite his own illness, except for his threat to kiss audience members to prove his immunity.

Trump made a local pitch, hammering home the claim that a Democratic administration could limit fracking in areas where the economy is heavily dependent on energy, despite Biden's proposal to only bar new leases on federal land, a fraction of U.S. fracking operations. And Trump, touting his elimination of a federal rule that would have brought more low-income housing to the suburbs, zeroed in on groups whose support he has struggled to retain, including female voters turned off by his rhetoric.

“So I ask you to do me a favor. Suburban women: Will you please like me? Please. Please. I saved your damn neighborhood, OK?" Trump said. “The other thing: I don’t have that much time to be that nice. You know, I can do it, but I gotta go quickly.”

Biden spent the day in Florida, his third visit to the state in a month, looking to expand on his inroads with older voters. To Trump, "you’re expendable, you're forgettable, you’re virtually nobody,” Biden said at a senior center in Pembroke Pines, about 20 miles (32 kilometers) from Fort Lauderdale.

The “only senior Donald Trump seems to care about" is himself, Biden added.

After frequently criticizing Trump for not doing enough to promote mask wearing to prevent the spread of the virus, Biden was wearing two masks, an N-95 underneath a blue surgical mask, as he deplaned in Florida. Later in the day, he switched to his normal mode of donning just one.

Introducing Biden in Pembroke Pines, Democratic Rep. Debbie Wasserman Schultz noted that “neither of these men will walk into the White House without the blessing of Florida seniors.”

“Much is made of the rise of the youth vote, and thank God for it," the Florida congresswoman said. "But it’s residents 65 or older who still swing elections in the Sunshine State.”

Biden also held a drive-in rally designed to promote voter mobilization in the heavily African American community of Miramar. His swing coincided with a $500,000 donation from billionaire former New York Mayor Mike Bloomberg to increase Democratic turnout in Miami-Dade County.

“I'm running as a proud Democrat, but I will govern as an American president,” Biden said to supporters blaring their horns as they listened from cars. “I'll work as hard for those who vote against me as those who vote for me."

Back in Washington, Tuesday marked a second day of Senate hearings to confirm Amy Coney Barrett to the Supreme Court. Trump and top Republicans see a swift confirmation as a chance to energize conservatives. Trump mentioned those proceedings as he left the White House, saying, "Amy was doing incredibly well.”

Biden's campaign believes it can win the White House without Florida's 29 electoral votes, but it wants to lock up the state to pad a margin of victory over Trump, who has questioned the legitimacy of an election where many people will cast mail-in ballots during the pandemic. Biden has vowed to win Pennsylvania, but if he falls short, his path to victory narrows substantially.

With 20 electoral votes, Pennsylvania is anchored by Philadelphia to the east, Pittsburgh to the west. But the rest of the state is largely rural, comprised of small cities and towns where Trump ran up the score four years ago. He will need to again, in even greater numbers, as his prospects have slipped since 2016 in places like vote-rich suburban Philadelphia, where he underperformed by past Republican measures.

Trump's rally was at the airport in Johnstown in Cambria County, a historically coal and steel area that narrowly backed Democrat Barack Obama in 2008. But it has trended Republican for the past three decades and, in the 2016 election, Trump scored a 37 percentage-point victory. The area is also substantially whiter and has lower median incomes and lower rates of college-degree attainment than the rest of Pennsylvania.

Biden, who was born 220 miles (350 kilometers) away in Scranton, visited Johnstown late last month. The former vice president has tried to cast himself as a champion of working-class voters while accusing Trump of focusing instead on stock market returns and Park Avenue values.

Despite the pandemic, Trump’s campaign has prioritized in-person events and aggressive door-knocking as it tries to turn out new and low-propensity voters, including more members of the white working class who may have backed Democrats in the past.

Republicans point to an aging population and a shrinking voter-registration edge for Democrats, down 20% from 2016’s election to 717,000, according to the latest Pennsylvania data.

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Weissert reported from Washington; Lemire from New York; Barrow from Pembroke Pines, Fla. Associated Press writers Thomas Beaumont in Des Moines, Iowa, and Marc Levy in Harrisburg, Pa., contributed to this report.