A worker processes mail-in ballots at the Bucks County Board of Elections office prior to the primary election in Doylestown, Pa., May 27, 2020. Associated Press File Photo

HARRISBURG — Pennsylvania’s highest court on Friday said it will consider whether counties must accept provisional ballots cast on Election Day at polling places by voters whose mail-in ballots lacked secrecy envelopes or were rejected for other flaws.

It could determine the fate of thousands of votes that could otherwise be canceled in the Nov. 5 election, when Pennsylvania is considered a critical state in the presidential contest.

The Supreme Court took up the appeal from a Commonwealth Court decision just two weeks ago that said Butler County had to count provisional ballots from two voters who had received automatic emails before the April primary telling them their mail-in votes had been rejected because they were so-called “naked ballots” that weren’t enclosed in the provided secrecy envelope.

When the two voters tried to cast provisional ballots, elections officials in Republican-majority Butler County rejected them, prompting a lawsuit. The voters lost in Butler County court but on Sept. 5 a panel of Commonwealth Court judges reversed, saying the two votes must be counted.

The case is among several lawsuits over the fate of Pennsylvania mail-in ballots cast by voters who failed to follow the rules in sending them in to be counted, most notably the much-litigated requirement for accurate, handwritten dates on the exterior envelopes. Democrats have embraced mail-in voting far more than Republicans since Pennsylvania lawmakers greatly expanded it five years ago, on the eve of the pandemic.

The decision to take the case comes a week after the Pennsylvania Supreme Court overturned Commonwealth Court in a separate mail-in ballot case, effectively allowing counties to enforce the exterior envelope date mandate.

The order issued Friday said the justices will consider whether counties must count provisional ballots cast by voters who fail to submit their ballot in a secrecy envelope — the issue that tripped up the two Butler voters. But the high court indicated it also may rule on the wider issue of permitting provisional ballots for voters whose mail-in ballots get rejected for other reasons.

The appeal was brought by the Republican National Committee and the Republican Party of Pennsylvania, which argued Commonwealth Court was establishing court-mandated ballot curing that is not authorized in state election law.

The Supreme Court set deadlines next week for the GOP entities, the two Butler voters who sued and the state Democratic Party that’s on their side as well as others who want to weigh in.

Provisional ballots that are typically cast at polling places on Election Day are separated from regular ballots in cases when elections officials need more time to determine a voter’s eligibility to vote.

County officials run elections in Pennsylvania. It’s unclear how many of the state's 67 counties do not let voters replace a rejected mail-in ballot with a provisional ballot, but the plaintiffs have indicated at least nine other counties may have done so in the April primary.

About 21,800 mail ballots were rejected in the 2020 presidential election, out of about 2.7 million mail ballots cast in the state, according to the state elections office.