A high number of absentee ballot requests from Maine voters overseas has led to a processing backlog at the Secretary of State’s Office, leaving some to wonder whether their votes have reached their destination.

Richard Giordano, a physician from Stonington who is working in London, said in an email to the Portland Press Herald that he mailed his ballot Oct. 15 but has yet to receive confirmation that it was received. He contacted an election official in Maine, who told him that the Secretary of State’s Office is behind in entering absentee ballots that have come in by mail.

Kristen Muszynski, a spokeswoman for the Secretary of State, said that despite the delays, the staff is confident that all ballots will be entered before Election Day.

Muszynski said the state had issued 4,495 ballots, either electronically or by mail, to voters overseas as of Wednesday. Of those, only 1,135 had been entered into the system and another 2,000 were pending.

“Overseas ballots are the only ones that are processed in-house at the Secretary of State’s Office, not by the towns,” she said. “It’s all hands on deck here. People shouldn’t panic.”

Voters can check the status of their ballots online at: http://maine.gov/sos/cec/elec/voter-info/uocava.html. Muszynski said that page is being updated daily.

Among those who can request overseas ballots are active-duty military members, merchant mariners, students and people who have temporary work assignments.

Already, the number of overseas ballots issued this year has eclipsed the total from 2012. Ballots can be requested through Election Day, so the number is likely to rise, another measure of interest in a polarizing presidential race. In 2012, Mainers overseas requested 4,479 ballots, and returned 3,336.

The total number of absentee ballots requested in Maine through Nov. 1 was 220,696. That’s significantly ahead of the 197,275 issued in 2012 but still shy of the 243,989 issued for the 2008 presidential election.

Thursday is the final day for Mainers to vote early by submitting in-person absentee ballots before the Nov. 8 election.

Muszynski said it’s rare that a mailed ballot would be lost, but if someone is concerned about that possibility, they can request an electronic ballot. Even if the paper ballot then shows up, an election official who tried to enter that ballot into the system would see that an electronic ballot had been submitted by that voter.

“Our focus has really been in making sure we’re issuing ballots to everyone that wanted one,” she said. “Now that we’re processing more and more, people can check daily to see if their ballot has been entered.”

Giordano said in an email Wednesday he has requested an electronic ballot just to be sure that his vote is counted.

Correction: This story was updated at 10:05 a.m. on Thursday, November 3, 2016 to correct the spelling of the spokeswoman for the Maine Secretary of State.