President Trump on Friday tweeted vague questions about thousands of military ballots that have not yet been counted in Georgia as his odds of reelection diminished, in an apparent effort to raise doubts about the integrity of the election process.

“Where are the missing military ballots in Georgia?” Trump tweeted. “What happened to them?”

The questions came after former vice president Joe Biden pulled ahead of him in the presidential race in Pennsylvania, following an arduous, multiday effort to count ballots nationwide. Trump has alleged without evidence that widespread fraud by Democrats hampered his campaign.

Trump has accused Democrats in several states of turning the election process against him. As he also fell behind in Georgia — a longtime red state with a Republican administration — he raised military ballots as an issue instead.

While the rules vary by state, military ballots in Georgia must be postmarked by Election Day and received by Friday by 5 p.m. As of Friday afternoon, 18,008 military ballots had been accepted and 8,410 were still out with the possibility of return, Georgia officials said.

“There are ballots that are gonna make it, there are ballots that are not gonna make it,” said Gabriel Sterling, the voter systems manager for Georgia Secretary of State Brad Raffensperger’s office. “We are going to count all the legal ballots.”

Trump has repeatedly alleged without evidence that mail-in ballots were subject to widespread fraud, a charge that past studies have rebutted. The Postal Service’s speed has slowed since Postmaster General Louis DeJoy, a Trump ally, implemented cost-saving measures this summer, outraging Democrats who knew the election would rely heavily on the mail amid the coronavirus pandemic.

The number of ballots still out left the mathematical possibility of Trump retaking the lead from Biden. Because of the razor-thin margin between the two candidates in a contest with nearly 5 million votes, there will be a recount, Raffensperger announced Friday. Any military ballot postmarked by Tuesday that was received by Friday will be included.

Urban and suburban counties where Biden has outperformed Trump so far had the most military ballots outstanding, including Fulton with 956, DeKalb with 802 and Gwinnett with 741, according to data released Friday afternoon. Those could include service members anywhere in the world who are still registered in Georgia.

Fulton County, Georgia’s most populous, has received at least 900 military and overseas ballots in the last few days and expects to process them and report their results to the secretary of state by Friday evening, county elections director Richard Barron said.

Counties with a military base nearby and a significant number of outstanding ballots include Cobb, home to Dobbins Air Reserve Base, with 569; and Muscogee, outside Fort Benning, with 323.

Some 500 military ballots had been returned between Thursday and Friday. Based on past years, it was likely that several thousand of the outstanding ballots either will not be returned at all, or will not arrive in time, casting doubt on whether there were enough to flip Georgia back in Trump's favor.

“I don’t think that one would see a significant movement, even with it as close as it is in Georgia,” said Scott Cooper, a spokesman for Count Every Hero, a nonpartisan effort to ensure that military ballots are counted.

But Cooper, a retired Marine Corps officer and past Democratic candidate for Congress, said every ballot should be counted and suggested that there are lessons that can be taken from what happened in Georgia. Despite being home to large military installations, the state has among the strictest laws in the nation for returning military ballots, leaving the voice of many service members who vote unheard each election, he said.

“It really gets me fired up when these guys and gals send in their ballots and they don’t get there in time,” he said. “That’s not right.”

Cooper drew a comparison between Georgia and North Carolina, which allows service members to return their ballots by mail, fax or email. Votes received by mail in North Carolina are typically counted 10 days after a general election, and do not require a postmark.

Alex Horton and Reis Thebault contributed to this report.