Trump and Biden are poised for a rematch in Pa. Here’s what’s changed since 2020.

In the last two months, President Joe Biden landed in Marine One amid log cabins at Valley Forge National Historical Park and former President Donald Trump touched down in his “Trump Force One” branded jet at Philadelphia International Airport for a quick pop-in at a sneaker convention.

They’re becoming Pennsylvania frequent fliers.

Trump called the state “one of the most important battlegrounds” at a Harrisburg rally this month, while Biden said Philadelphia was “the backbone of my campaign” during a December fundraiser.

As both appear poised to be their parties’ nominee, which man returns to the Oval Office could very well be decided by Pennsylvania voters. With the most electoral votes of any swing state and a history of narrow margins in presidential races, Pennsylvania isn’t just a bellwether for how the country shifts politically but a geographic road map for how each candidate can win again.

So what will it take for Trump or Biden to win the state this year? There are many key factors.

Trump won the state by 44,000 votes in 2016, roughly the capacity of Citizens Bank Park. Biden took it in 2020 by about 80,000 — just under the population of Upper Darby.

The last four years have been a split story in Pennsylvania. Republicans have continued to gain on Democrats in overall registration, cutting their deficit in half compared to 2020 and now trailing by just 3.4%. (Voters registered with third parties have increased only slightly.) Democrats, meanwhile, have had close-to-perfect election success, winning nearly every contested statewide seat since 2016.

This year, with an electorate dissatisfied by both candidates, it’ll be a battle for base turnout and disengaged voters.

”They’re gonna be playing within the margins,” political strategist Mustafa Rashed said. “We’re looking at the same story as 2016, when 40,000 votes won a whole state so both candidates have to turn up the noise with their base.”

When Trump raised a gold high-top shoe before an audience of sneaker enthusiasts in Philadelphia last weekend, he wasn’t just promoting his newest merch but pitching himself to a Democratic city where he sees political opportunity.

Democrats have long relied on Philadelphia, which reliably delivers more votes for their statewide candidates than other counties. But lately, the city’s vote share has dropped and its turnout rates have lagged relative to the rest of the state.

“The driver for Democratic success always starts in Philadelphia,” said Chris Borick, director of the Muhlenberg College Institute of Public Opinion. “The margin that comes out of there can be make or break and the concern among Democrats is what’s the ability of the city to take on that role?”

Add to that the problems Biden faces with younger, progressive voters who disagree with his policies in the Middle East.

Polls show Black and Hispanic voters, specifically younger men, are not supporting Biden at the levels they were in 2020. And while his age remains a problem for the majority of voters, younger voters say they’re particularly concerned with his ability to serve at 81.

“Down 20 points among liberals, that’s his Democratic base,” Franklin and Marshall pollster Berwood Yost said. “He’s gotta reassemble that.”

Biden’s campaign has already staffed up in Pennsylvania and hired longtime Philadelphia Democratic strategist Kellan White specifically to focus on the city, where an internal battle is brewing between traditional Democrats and progressives.

“I know that when people are meaningfully engaged in Philadelphia they turn out,” White said. “And we’re not gonna start in September, we’re gonna start as soon as possible.”

The campaign will also have the benefit of elected Democrats stumping for Biden, including Gov. Josh Shapiro and Sen. John Fetterman, along with grassroots groups going door to door, unlike in 2020 when the pandemic largely shut down in-person canvassing.

In last year’s mayoral election, turnout increased citywide but an Inquirer analysis showed turnout dropped in many Black and Hispanic precincts.

“These areas feel the brunt of inflation and rising prices,” said Robert Saleem Holbrook, a progressive organizers and the executive director of Straight Ahead, the nonprofit arm of the Abolitionist Law Center. “Fear of Trump is not going to cut it for these communities because they are used to living in fear and/or economic uncertainty.”

Philadelphia is part of Trump’s equation, too; it’s home to the 10th largest number of registered Republicans in the state.

“It’s not just rural areas,” said Philadelphia GOP Chair Vince Fenerty, who supports former South Carolina Gov. Nikki Haley in the GOP primary. “Republicans here in the city of Philadelphia, they feel strongly about Trump.”

Trump’s national press secretary Karoline Leavitt predicted memories of Trump’s first term would propel him across the state.

“President Trump took care of Pennsylvanians by lowering gas prices, grocery bills, and interest rates to record lows, securing the southern border, demanding law and order, and delivering peace around the world,” Leavitt said.

Dominic Chickilly joined several thousand fellow Trump supporters for the former president’s rally in Harrisburg earlier this month.

“Pennsylvania is Trump country,” said Chickilly, a 32-year-old window-maker from Schuylkill County.

Trump could benefit from GOP registration gains in many places that voted heavily for him in 2020.

Fayette County gained 3,000 Republicans since 2020, going from 43% Republican in 2020 to 49% as of January, the largest increase of any county. Democrats lost about 6,000 voters on the rolls.

Michelle Mowry, who chairs the GOP committee there, said the increase is largely former Democrats or previously disengaged residents.

“Basically, We the People are pissed off, and they’re rising up to get behind a leader that has proven he puts Americans first,” she said.

GOP gains in registration occurred statewide. However, that can be a lagging indicator of how people vote. Plenty of voters in Pennsylvania remained registered Democrats in 2016 and 2020 despite having long since abandoned the party for Trump. Democrats also made huge gains in registration after Trump’s election in 2016, leaving less room for them to grow.

While Trump lost Pennsylvania in 2020, he got more votes than he did in 2016. To win the state again, he needs to hold on to those largely white, postindustrial counties, and rural areas, many of which are losing population.

“One really impressive thing for Trump in 2020 was his ability to outperform even the record numbers of 2016 in the state,” Borick said. “There’s a few less folks that are in those places that he dominated now … He’s gonna have to find even more ways to increase turnout. How he can do that is not abundantly clear.”

In 2016 the state showed a massive shift toward Trump compared with former President Barack Obama’s performance in 2012. The state’s shift back to Biden in 2020 was much smaller, but just enough.

Biden won, in part, by eating into some of Trump’s margins in rural areas, and Democrats like Shapiro built on that trend in the midterms.

“We won several counties that no Democrat had won in many generations from Beaver to Cumberland, to Luzerne,” Shapiro said. “If you go back and look at the areas, those would be areas I’d encourage the Biden campaign to take a look at.”

But both Shapiro and Fetterman, who drove up support in nontraditional Democratic areas, had higher approval ratings than Biden does.

Democratic strategist J.J. Balaban thinks it’s more likely that 2024 looks like 2016 for Democrats in rural areas. “I think you’ll see Biden get down to Hillary [Clinton] levels or worse in rural areas. That doesn’t necessarily mean he loses the way Hillary lost because you’ll see more suburban challenges for Republicans than previously.”

Shortly after a Democratic candidate won a Pennsylvania state House seat in a Bucks County special election this month, Biden’s campaign blasted out an email, claiming victory for Democrats.

Few people outside of the region even knew that race was happening. But the district, in the swing county, which leaned Democratic, represents a core part of the Democrats’ suburban plan.

While Bucks remains a divided battleground, the Philadelphia suburbs have been a blue bastion — and were the only area where Democrats added modestly to their voter rolls.

“We go into this with clear eyes about how competitive Pennsylvania is,” Biden campaign adviser Brendan McPhillips said. “But we have a trump card in that Joe Biden is Pennsylvania. People know Joe Biden here in a personal way, they identify with him, with his family, who how he’s been brought up with his values and his character in ways that Trump never can.”

Democratic statewide wins since 2020 have been fueled in large part by suburban voters. Abortion rights has been a major theme in many of those races.

“The Democrats have done a masterful job of framing Republicans … as extremist and out of touch people who want to take women’s rights away,” Delaware County GOP chair Frank Agovino said. “It’s really not true.”

Agovino’s county has seen the steepest decline in Republican registrations — a loss of 14,000 Republican voters from the rolls there since 2000.

He’s advised Republicans, including Senate candidate Dave McCormick, to talk more directly and specifically about abortion by indicating the number of weeks of pregnancy through which they think the procedure should be legal.

“That’s still the big issue as far as winning these statewide elections and winning Delaware County,” Agovino said. “I don’t think [Republicans] can win Pennsylvania unless you perform better than we’ve been performing in Delaware County.”

As Democrats keep growing their support in the Philly suburbs, voters in midsize suburbs around Harrisburg and Allentown — some of the fastest-growing the state — are also shifting blue.

Take Dauphin County, home to Justin Douglas, a progressive pastor and community organizer, who won a seat on the board of commissioners and helped flip the county to Democratic control for the first time since the Civil War. Biden’s campaign called Douglas shortly after his win and asked him to introduce the president at a January event.

Douglas won election in part by focusing on local issues instead of national divides. But he sees good news for Democrats in the region. And he thinks Biden’s anti-extremism messaging resonates there.

“Biden, in my estimation, is more representative of the values that drive the average person in Dauphin County, the average American,” Douglas said. “I believe that free and fair elections, democracy being a high ideal, made in America, bringing jobs to America, these are things he’s not only done but he’s continuing to do.”