HARRISBURG, Pa. (AP) — Pennsylvania vote counters edged closer to wrapping up their tallies Friday, with mail-in votes giving Democrat Joe Biden a narrow lead in the fight for the state's cache of 20 electoral votes.

Republican President Donald Trump needs to pull off a repeat of his 2016 victory in Pennsylvania to have a shot at reelection.

Pennsylvania elections officials were not allowed to process mail-in ballots until Election Day under state law, and those ballots have skewed heavily in Biden’s favor after Trump spent months claiming without proof that voting by mail would lead to widespread voter fraud.

The millions of mail ballots from across the state are overwhelmingly breaking in Biden’s direction.

There’s also a possibility the race won’t be decided for days. If there is less than a half percentage point difference between Biden’s and Trump’s vote totals, state law dictates that a recount must be held.

Some of the state’s most heavily populated locales, including Montgomery and Chester counties in the Philadelphia suburbs, reported finishing their tallies.

The Trump campaign has tried to stop the count in Philadelphia itself — alleging city officials were depriving their observers of meaningful access — but a federal judge refused to go along, instead urging the sides to forge an agreement. Speaking from the White House on Thursday night, Trump made unsupported allegations that Democrats in Pennsylvania and elsewhere were trying to steal the election.

The Trump campaign and the Republican Party argued in court Thursday that GOP election observers were kept too far away from the tabulation in Philadelphia, that some Democratic-leaning counties unfairly allowed people to fix technical problems with their mail-in ballots, and that mail-in ballots arriving after Tuesday should not be counted.

His campaign scored one tentative legal victory as an intermediate state appeals court on Thursday granted more access to party and candidate observers, allowing them to get closer — 6 feet (2 meters) away — to election workers processing mail-in ballots in Philadelphia.

The Trump campaign later filed an emergency action in federal court, asserting the city had failed to comply with the state court order. The campaign asked a federal judge to halt the count “so long as Republican observers are not present as required by state law.”

The city insisted it had moved barricades as ordered, even as it appealed the state court ruling to the Pennsylvania Supreme Court, citing concerns over worker safety amid the coronavirus pandemic and the potential for intimidation.

At a Thursday evening hearing, U.S. District Judge Paul S. Diamond, an appointee of former GOP President George W. Bush, told the Trump campaign and city officials to work it out. He expressed exasperation as lawyers bickered about which side was following the rules.

“Really, can’t we be responsible adults here and reach an agreement on how far all observers are allowed to stand?” said Diamond, suggesting each party be allowed 60 observers inside a hall at the downtown Philadelphia convention center where the ballots are being tallied.

“The whole thing could (soon) be moot," he said.

It was unclear whether any of the legal challenges would make a difference to an eventual outcome.

More than 2.6 million mail-in ballots were cast, and there has been no report of fraud or any other problem with the accuracy of the count.

Allegheny County, where Pittsburgh is, wrapped up the initial vote count but had to wait until Friday to tabulate more than 35,000 mail-in and absentee votes. The delayed count of 29,000 of those votes stemmed from an earlier glitch involving voters who were initially mailed ballots with the wrong contests on them. The county issued corrected ballots but said it would review them to make sure they were counting only one ballot per voter.

Other ballots that will be reviewed include ones that couldn’t be scanned, or that were missing a date or had an illegible voter declaration, said county spokesperson Amie Downs.

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Associated Press writers Marc Levy in Harrisburg, Michael Rubinkam in northeastern Pennsylvania and Maryclaire Dale and Claudia Lauer in Philadelphia contributed to this report.

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Find AP’s full election coverage at APNews.com/Election2020.