ATLANTA — The election workers sat two to a table, a stack of ballots off to the side. One auditor lifted a ballot, reviewed the selection for president, and handed it to the other to do the same before placing it in the right pile — TRUMP, BIDEN, JORGENSEN or WRITE-IN — or setting it aside for further review.

The effort was part of a historic manual recount of presidential votes in Georgia, where hundreds, if not thousands, of workers in the state’s 159 counties on Friday began the tedious task of re-tallying each of the nearly 5 million votes cast and checking for any potential irregularities.

The recount, the largest hand recount in U.S. history, was ordered by Republican Secretary of State Brad Raffensperger in an effort to reassure the public about the outcome of the presidential election in his state, where President-elect Joe Biden was projected to win with a lead of about 14,000 votes over President Trump.

Research shows that recounts do not typically change the results by enough votes to flip the outcome. Nevertheless, the narrow margin, the fact that Georgia historically has been a red state, and efforts by Trump and top GOP officials to cast doubt on Biden’s victory in the presidential contest have led to this extraordinary effort.

Election workers across the state, and employees temporarily reassigned from other county departments, are toiling away through the weekend to meet the Wednesday deadline for completing the recount. They are powering through the pressure of being under a national microscope and the fatigue of administering an election during a pandemic.

“The eyes of the state and the nation are on you guys,” said Chris Harvey, the state’s elections director, during a training for county employees this past week. He then reminded them that while the process may seem daunting, it comes down to a simple task: “counting pieces of paper.”

Still, this is laborious work.

In Cobb County, a suburban enclave north of Atlanta, the audit began at 9 a.m. Friday in a sprawling park and event center. The process started with more than 50 election workers — a number that was expected to swell as the count wore on — at rows of tables in teams of two.

The first worker examined the ballot and read aloud the name of the candidate who received the vote, then handed the ballot to the second worker who did the same and added it to that candidate’s pile. Once they finished with a batch of ballots, both workers counted — one by one — how many votes each candidate received. Disputed ballots were placed in separate piles, to be reviewed by a separate panel.

At table after table, pairs of workers repeated this process until all ballots were counted.

Meanwhile, observers from both parties strolled through the aisles and watched. Each party is allowed the same number of official observers, who must preregister with the county.

Janine Eveler, the head of Cobb County’s elections office, said she and her staff have been working nonstop since Election Day.

“Many of my staff have been working long, long hours many days in a row,” Eveler said.

“I’m tired,” she added, noting with a laugh that “my husband still knows who I am” but they haven’t had much time together recently.

Through the recount, staffers will work from 8 a.m. until 6 p.m. and will stay through the weekend, she said. But she was bracing for last-minute staffing changes, since the county had not gone through this process before.

“It’s all new,” she said.

Raffensperger ordered the recount under the state’s new risk-limiting audit process, enacted as part of a 2019 election overhaul. Originally, the requirement was to select a random, statistically significant sample of ballots to be reviewed by auditors to make sure ballots were accurately counted.

But because Biden’s margin is so narrow, at just 0.3 percent, state officials decided it would be easier to examine every ballot. So election officials must do a manual check of each ballot to ensure they were properly scanned by machines.

Counties are footing the bill for the audit. The price tag is not yet known, but DeKalb County, which includes a slice of Atlanta and its suburbs, estimated the manual recount will cost it $180,000.

In several counties, the process is being live-streamed. The recount is open to observation by members of the public and media, and state election officials have placed a heavy emphasis on transparency, which they say is crucial to refuting unsubstantiated claims of irregularities and conspiracy theories.

After counties submit their results by the end of the day on Wednesday, the secretary of state is expected to certify the statewide election results by Friday. But because the margin is below 0.5 percent, the Trump campaign can still request another recount within two business days of the state’s certification of results, which would require election officials to re-scan all the presidential ballots once more.

In Fulton County, Georgia’s largest and home to Atlanta, elections staffers were setting up their immense recount operation on Friday at the Georgia World Congress Center, a convention complex downtown.

Richard Barron, the county’s elections director, said his office will have 250 workers reviewing each of the 528,777 ballots cast by Fulton residents. The workers will all be county employees, some from the elections office, but about 300 others who have been reassigned from other parts of the county government. He said he expects the recount to last until at least Monday.

It’s already been a trying election season for the county, which faced fierce criticism after a disastrous primary election in June, marked by troubles with new machines, long lines and voters who said they never received their absentee ballots. After a smooth Election Day, the county became a target of baseless accusations of tampering, which officials roundly denied and debunked.

The intensive hand audit and impending Senate runoffs in January come as the county prepares for two additional elections — a special election for Congress and a state Senate race. And Barron’s team is exhausted.

“We have had no time to rest,” Barron said. “None of us have really had any time off in the last few months. I think a lot of people are really tired.” But, he added, “we know we have to push forward through January and we’re committed to do that.”

Fulton County’s elections office has also battled severe coronavirus outbreaks that have sickened 28 staffers and killed one.

The recount means workers will need to spend more time inside, near other people. But Barron said he’s confident the convention center room — at 110,000 square feet — will give staff members enough space to safely distance.

Counties are permitted to decide whether those working the recount need to wear masks or other protective gear. Live feeds of several other counties showed not every county required such protection, and in some cases, older workers were in tight quarters indoors without any masks on.

Clayton County drew international attention on election week as staffers worked overnight to tabulate the ballots that eventually put Biden ahead of Trump in the state. On Friday morning, plexiglass barriers separated the teams of auditors, who were clad in matching county shirts that read “VOTE.”

And in DeKalb, officials announced a rigorous set of coronavirus-related guidelines for its recount process.

They’re repurposing one of the county’s largest early-voting sites — an old Sam’s Club big-box store — for the audit, which involves two teams of 150 staffers each, working in shifts. Officials said Friday that everyone who enters the building must wear a surgical-grade mask and that homemade face coverings won’t be allowed. Anyone who refuses to wear a mask will be turned away, they said.

Volunteers from the county’s health department will sanitize surfaces in the counting room between workers’ shifts.

“We want to be sure this does not result in any unanticipated outbreaks,” DeKalb County’s Health Director Sandra Ford told reporters Friday.

The county must recount more than 370,000 ballots, but Elections Director Erica Hamilton said her staff is prepared.

“The general mood of our poll workers is enthusiastic,” Hamilton said. “They may be a little tired, but they’re ready for this.”

In Forsyth County, a Republican stronghold where Biden cut into the party’s traditional margin, the first day of the audit went without much incident. Thirty election auditors who worked for the county sat side by side at 15 tables. As in other counties, they reviewed each ballot, saying out loud which presidential candidate had won them, then placing them in stacks. A separate panel of five Democrats and five Republicans reviewed disputed ballots.

Few ballots fit into the disputed categories, and by 1 p.m. Friday, when counters broke for lunch, 20,000 of the county’s nearly 130,000 valid ballots had been tallied. All of it was witnessed by partisan observers who could walk from table to table, and by a separate group of public observers, who watched behind caution tape.

“It’s been moving pretty well,” said Joel Natt, an assistant secretary of the board of elections, and a Republican Party activist, who was helping run the count. “We’re learning as we’re going.”

Dave Weigel in Atlanta contributed to this report.