The elections director for Butler County, Pennsylvania says that an unknown number of mail-in ballots, potentially thousands, have been lost by the postal service.

According to KDKA-TV, the county sent about 40,000 ballots to voters but many of those voters report that their ballots never arrived in the mail.

Voters and election officials are confused by the missing ballots. Officials initially believed that there was simply a delay in the postal system.

"At first we thought that maybe it just was a delay in the postal system" due to high volume, Leslie Osche, chair of the Butler County commissioners, told KDKA-TV. "And that could still be the case. But nonetheless, when we realized that, we changed our strategy and now have begun to tell folks that if they haven't received a ballot, they still have multiple options."

The Postal Service says it is not aware of any significant delays or issues delivering mail in Butler County.

"Regarding mail sorting and delivery in Butler County, the Postal Service is unaware of any significant delays or issues and is in regular contact with the Board of Elections as we work to locate and deliver ballots as they are presented to us," the Postal Service said in a statement.

Voters who did not receive their ballots are encouraged to go to the elections office to vote in person, vote via a provisional ballot at a polling place, or call the elections bureau to have a sheriff's deputy hand-deliver ballots to those who cannot leave their homes.

According to the Pittsburgh Post-Gazette, only 24% of the nearly 40,000 registered voters who requested mail ballots have returned them to the county.

Pennsylvania, a key swing state in the 2020 presidential election, is expected to receive a record volume of mail-in and absentee ballots because of the coronavirus pandemic. State law prohibits election officials from beginning to count received ballots until 7 a.m. ET on Election Day. Each county in Pennsylvania has a different process for counting ballots and Fox News reports it is likely that all of the absentee ballots won't be counted by the end of Election Day.

Additionally, the Pennsylvania Supreme Court ordered that the deadline to submit and count ballots processed by mail be extended to Friday, Nov. 6, a full six days after the election. State Republicans have appealed the decision to the U.S. Supreme Court, which will likely hear the case after the election. If the high court rules overturns the Pennsylvania Supreme Court ruling, ballots received after Election Day may be disqualified.