Joe Biden held drive-in rallies in Bucks and Luzerne Counties on Saturday, pitching himself as a native son of Pennsylvania and the candidate best able to unify a fractured nation. His twin appearances in politically competitive areas of a pivotal swing state launched his presidential campaign into the final 10 days before Election Day with a hopeful message not unlike the one that first lifted his former boss Barack Obama to the White House.

At both events, when he talked about bringing the country together amid a pandemic, a sagging economy, and deep political and cultural divisions, Biden quoted John F. Kennedy’s remarks about the challenge of putting a man on the moon.

“He said we’re gonna do it because we refuse to postpone," Biden said as more than 100 cars and trucks decorated with Biden signs and flags honked in support in a parking lot in Bristol, the location of the first rally about 20 miles northeast of downtown Philadelphia. "I refuse to postpone the work we must do.”

And Biden urged voters to show President Donald Trump what America is about.

“We choose hope over fear. We choose unity over division. Science over fiction. Truth over lies. And yes, honor and integrity over lying,” Biden said. “It’s time to stand up. Let’s take back our Democracy now. We can do this. There’s nothing we cannot do.”

Biden’s swing through Pennsylvania came a day after Republicans again asked the U.S. Supreme Court to overturn a mail ballot deadline extension ordered by the state’s highest court. The filing late Friday by the state GOP marked a rapid return to an issue on which the Supreme Court had only just deadlocked, and raised the prospect of a different outcome after a new justice is installed next week.

And it came as the former vice president’s most high-profile supporters kick into overdrive their efforts to make sure Democratic voters cast their ballots, while Biden concentrates his efforts on courting white working-class swing voters. Sen. Bernie Sanders, Biden’s rival in the primary, held two events in Pittsburgh to boost the Democratic nominee. And Obama, who held a drive-in rally in Philadelphia on Wednesday, campaigned for Biden in Miami.

Pennsylvania is widely viewed as the state that could decide the election. And Biden, with his wife Jill, asked Pennsylvanians to support him by saying he’s just like them.

“Jill’s a Philly girl, but I’m a Scranton guy, and it’s good to be almost home,” Biden said in the small Luzerne County borough of Dallas, about 25 miles west of his childhood hometown.

“I say it’s about time a state school guy gets to go to the oval office," he said as the wind whipped his suit jacket. "Because you know what? If I’m sitting there, you’ll be sitting there with me.”

Trump won’t be in the state this weekend, but he has two rallies scheduled for Monday — one in Lancaster County and the other in Blair County. Nikki Haley, Trump’s former ambassador to the United Nations, met with Indian American voters on Saturday in Norristown before hosting a second event in Reading. She’ll host another campaign event Sunday in West Brandywine Township, Chester County. And Eric Trump also campaigned Saturday in the Poconos region.

In a call with reporters Saturday, the Trump campaign skewered Biden for saying during Thursday’s debate that he wants to “transition away from the oil industry."

The Trump campaign sees that remark as one it can capitalize on in the homestretch of the race. Lou Barletta, a Republican former congressman from Northeastern Pennsylvania, called it “a death sentence” to the state’s oil and gas industry.

“Our economy and future here in Pennsylvania would be crushed by his plan, the very state that he claims that he loves so much,” Barletta said, adding that he received text messages from people across the state during the debate expressing concern. Among those concerned, he said, were people in Philadelphia’s building-trades unions.

“I think you’re going to see a swing in votes in Philadelphia because of that,” Barletta said. “The building trades, many of them are dependent on those types of jobs.”

But it’s far from clear that his debate comment will do anything to significantly impact a race that has been largely frozen in place, with Biden consistently leading Trump by high single-digits in Pennsylvania and low double-digits nationally. A Morning Consult poll conducted after the debate found that 52% of independents and even 41% of Republicans support a transition away from the oil industry.

The Trump campaign also falsely claimed on the call that Biden’s environmental policies would eliminate more than 600,000 Pennsylvania jobs.

Biden said at the rally in Luzerne that he would get rid of federal subsidies for oil companies, not dismantle the industry.

» READ MORE: Trump held his own in Bucks County in 2016. But it might be slipping away in 2020.

While Biden is expected to win handily in most of the suburbs that surround Philadelphia, Bucks County could be more of a battleground. Trump lost the county only narrowly to Hillary Clinton in 2016. And Luzerne is one of three counties in the state that twice backed Barack Obama before swinging to Trump.

The Luzerne stop, in particular, keeps with Biden’s focus on trying to win back voters in places that not long ago supported Obama. Luzerne was the epicenter for that kind of switch last election: It produced a 32,200-vote swing from Obama to Trump in 2016, the largest such shift in Pennsylvania.

» READ MORE: A Pennsylvania county voted for Obama twice. But it’s ‘Trump Country’ now.

When Biden began speaking Saturday morning on a stage decorated with pumpkins and bales of hay, he told supporters how badly he wished he could greet them if it weren’t for the pandemic. Biden’s relatively small and socially distanced drive-in rallies stand in sharp contrast to the large rallies Trump continues to hold almost daily over the objections of public health officials.

“I don’t like the idea of all this distance,” Biden said. But "we don’t want to be super-spreaders.”

Trump, rallying supporters in North Carolina, complained about the focus on a pandemic that has killed more than 220,000 people in the U.S. “That’s all I hear about now,” he said. “Turn on TV, ‘Covid, Covid, Covid Covid Covid.’ A plane goes down, 500 people dead, they don’t talk about it. ‘Covid Covid Covid Covid.'”

Jill Biden spoke at both events and pitched her husband as a man who can bring Americans together. He has experience picking up the pieces, she said, rooted in the tragedy of losing his first wife and young daughter in a car crash.

“Through it all, he learned how to heal a broken family,” said Jill Biden, who touted her Philadelphia-area roots. “It’s the same way you heal a country. With love and understanding. With small acts of kindness. With bravery. With unwavering hope.”

Biden’s afternoon event in Luzerne featured Jon Bon Jovi, who Biden called a “national treasure.”

In the afternoon, Sanders hosted a drive-in rally with Lt. Gov. John Fetterman and State Reps. Sara Innamorato and Summer Lee, who both backed Sanders in the primary.

And Sanders attended a morning event with members of the SEIU to promote early voting, where he assailed Republican efforts to restrict the counting of mail ballots.

“We believe that we should make it easier for people to vote and to participate in the political process,” Sanders said. “And yet Trump and his friend are trying to suppress the vote.”

Staff writers Jonathan Lai and Jonathan Tamari contributed to this article.