PHILADELPHIA (CBS/CNN) -- Four key battleground states -- Pennsylvania, Nevada, Michigan and Georgia -- began Wednesday with tens of thousands of absentee ballots uncounted, leaving the White House race between President Donald Trump and former Vice President Joe Biden up in the air. In Pennsylvania, where officials couldn't begin processing hundreds of thousands of early ballots until Tuesday, counties made their own decisions about how to prioritize the crush.
Officials in Philadelphia have counted roughly 186,000 mail-in ballots out of 350,000 that had been returned as of Wednesday morning. Vote counting in the city continued through the night Wednesday.
Head of the Philadelphia City Commissioners Lisa Deeley refused to comment on when the ballot counting would be finished.
"We're doing the best we can to get that count done as soon as possible," Deeley said. "We'll be done as soon as we're done."
And Commissioner Al Schmidt says it won't stop until every eligible vote is counted.
"Philadelphia will NOT stop counting ALL legitimate votes cast by eligible voters," Commissioner Al Schmidt said. "And we will report and report and report until the last vote is counted. See for yourself:"
Eyewitness News is told more than 150 people are working eight-hour shifts and they will work 24-7 until every vote is counted.
Deeley says being able to count mail-in ballots before Election Day "certainly would have made a difference."
An updated count of mail-in ballots in Philadelphia County is expected later on Wednesday.
Election workers in Luzerne County, a northeastern county near Scranton, stopped counting mail-in ballots on Tuesday evening and will resume Wednesday morning, according to county Manager David Pedri. He said the county had counted about 26,000 mail-in ballots of roughly 60,000 cast.
Democratic-leaning Montgomery County, northwest of Philadelphia, planned to count "24 hours a day until completion," according to county spokesperson Kelly Cofrancisco.
Pennsylvania Gov. Tom Wolf said Wednesday morning that things are going as planned in the Commonwealth as the remaining ballots are being counted. He says he is committed to making sure the election result is accurate.
Pennsylvania Secretary of State Kathy Boockvar said the state is about 50% of the way through the mail-in ballot counting process, with millions still to be counted.
Republicans have filed a lawsuit challenging at least 1,200 absentee ballots in Montgomery County. A federal judge will hear the challenge on Wednesday morning.
Three Republicans observing the processing of mail-in votes described to a federal court how they saw absentee ballots with possible technical issues and believed elections officials might impermissibly try to give voters opportunities to fix ballots with issues that would have caused them to be thrown out. The Republicans alleged that the county had begun processing mail-in ballots too early and was illegally trying to allow voters to fix defects, such as by adding missing inner envelopes.
Also in Pennsylvania, GOP Rep. Mike Kelly and others filed a lawsuit in state court Tuesday evening accusing the Pennsylvania secretary of state of illegally advising that provisional ballots could be offered to absentee voters whose ballots would be rejected.
Officials in the states where ballots were still outstanding urged patience while the results are calculated. Pennsylvania Gov. Tom Wolf, a Democrat, released a video Tuesday evening cautioning voters to "remain calm" while the vote count is ongoing.
"Across the state, dedicated county workers are ready to tirelessly make sure everyone's vote counts," Wolf said.
The mail-in ballots, which smashed records this year as a result of the Covid-19 pandemic, are expected to favor Biden, whose campaign encouraged Democrats to vote early, while in-person votes on Election Day may have given Trump an advantage.
In three key states -- Michigan, Pennsylvania and Wisconsin -- election officials were not allowed to begin processing absentee ballots until on or just before Election Day, after Republican-led state legislatures successfully opposed changing laws to allow earlier preparations like other states.
After Biden spoke early Wednesday calling for patience while workers continued to count, Trump attacked the legitimate counting of votes and falsely claimed he had won in states where millions of ballots are yet to be counted.
The Republican National Committee has prepared for a large-scale legal battle that could come in a razor-thin contest in one of the key states. "We have thousands of volunteer lawyers and several law firms already on retainer in these battleground states," said RNC spokesperson Mandi Merritt.
Democrats have also amassed their own legal army to fight any potential court battles.
In Georgia, where rules allowed for pre-processing, major counties nevertheless reported backups and sent workers home rather than finish counting overnight.
Michigan Secretary of State Jocelyn Benson, who had suggested in the weeks before the election that counting could take until Friday, predicted to reporters Tuesday evening that the state could "potentially see a full result of every tabulation out of Michigan in the next 24 hours."
In Nevada, which Democrat Hillary Clinton won by a slender margin in 2016, the counting of mail-in votes in populous Clark County stopped overnight and was slated to resume at 11 a.m. ET Wednesday, according to the county's registrar of voters.
CNN contributed to this report.
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