ATLANTA (NewsNation Now) — Election officials in Georgia are beginning a hand tally of the presidential race, with all 159 counties required to start the count by 9 a.m. EST Friday.

County election officials must complete the hand tally by 11:59 p.m. Wednesday, according to the state. Georgia’s Secretary of State Brad Raffensperger has until Nov. 20 to certify the votes.

State law requires that one race be audited by hand to check that machines counted the ballots accurately, not because of any suspected problems with results.

Raffensperger chose to audit the presidential race, saying earlier this week that Georgia’s full hand recount is needed because the margin is so close.

There is no mandatory recount law in Georgia, but state law provides that option to a trailing candidate if the margin is less than 0.5 percentage points. Democrat Joe Biden’s lead stood at 0.28 percentage points as of Thursday afternoon.

Raffensperger said he expects it to take until the certification deadline to recount the votes.

For the hand recount, election officers will work with the paper ballots in batches, dividing them into piles for each candidate. Then they will run the piles through machines to count the number of ballots for each candidate. The scanners will not read the data on the ballots.

Once the results from the audit are certified, the losing campaign can request that recount, which will be done using scanners that read and tally the votes, Raffensperger said.

“The point of the audit is to show the machines counted the ballots fairly,” said Gabriel Sterling, who oversaw the implementation of the state’s new voting system for the secretary of state’s office.

Biden leads Republican President Donald Trump by 14,000 votes. There are no examples of similar recounts that have overturned leads of that magnitude.

The count comes as Raffensperger’s office announced his plans to quarantine after his wife tested positive for the coronavirus on Thursday.

Jordan Fuchs, the deputy secretary of state, told The Associated Press that Brad Raffensperger tested negative but planned to self-quarantine as a precaution. Fuchs clarified that the secretary’s quarantine will not affect the audit.

The audit is a new requirement that was included in a 2019 law that also provided guidelines that the state used to purchase a new election system from Dominion Voting Systems for more than $100 million. Doing a hand count of the nearly 5 million votes cast in Georgia during the Nov. 3 election is a massive task.

“It’s a tremendously bold undertaking, to hand count every ballot cast in a presidential contest, on basically an entirely new voting system, in the middle of a pandemic. It’s not a small enterprise,” said Mark Lindeman, the interim co-director of Verified Voting, a nonpartisan group that tracks voting technology and is providing technical support for Georgia’s audit.

Chris Harvey, elections director for the secretary of state’s office, sought during a training call Thursday to assuage any apprehension county election officials might be feeling.

“Keep in mind through all this stuff what we’re doing is relatively simple,” he said. “We’re identifying votes and counting pieces of paper.”

Candidates in Georgia’s runoff races will be hitting the campaign trail Friday. Republican Senators David Perdue and Kelly Loeffler, who are both running for reelection, are holding a rally in Cummings at 3 p.m. EST. Democrat Jon Ossoff will speak at events in Augusta and Athens Friday.

The state’s two runoff races will determine the majority in the U.S. Senate.