TALLAHASSEE — As several major Florida races face likely recounts, local election supervisors are working to verify thousands of votes that once again could flip high-profile contests that are too close to call.

Those provisional ballots, which can include absentee ballots without a signature or ballots cast in person by a voter whose eligibility is questioned, will be added Saturday to the first unofficial election results uploaded to the state.

That could mean 7,000 to 10,000 more votes added to the mix if history is any indication, according to election results from 2014 and 2016.

In 2014, for example, 7,199 provisional ballots were counted statewide. In 2016, there were 10,998, according to the Secretary of State’s Office. This midterm election's turnout of 62 percent, or more than 8.1 million ballots cast, fell between those two elections.

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Those additional votes could make a big difference in three close statewide races that could face a recount — the U.S. Senate race between Democratic incumbent Bill Nelson and Republican Gov. Rick Scott; the governor's race with Republican Ron DeSantis and Democrat Andrew Gillum; and the state agriculture commissioner race between Republican Matt Caldwell and Democrat Nikki Fried.

As of Thursday — two days after Election Day — six Florida races were heading toward recounts, an unprecedented number in a state where races sometimes are won by thin margins.

Under state law, a machine recount is automatic if the winning candidate’s margin is less than 0.5 percentage point, and a hand recount is required if the margin drops below 0.25 percent.

In addition to the statewide races, two state House races and a state Senate seat are expected to fall under the recount threshold. The Senate and agriculture commissioner races might qualify for hand recounts if their current margins hold.

Although there’s an unknown number of provisional ballots in the state's 67 counties that have yet to be tallied, the total count likely will affect races.

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The race for agriculture commissioner is the closest, with a margin of 577 votes, or less than 0.01 percent, in favor of Fried.

The Senate race margin is about 0.22 percent favoring Scott, while the governor's race is about 0.47 percent favoring DeSantis, according to Thursday results.

Hillsborough, historically a swing county, recorded 1,257 votes from provisional ballots in 2016 and 1,026 in 2014, while Republican Lee County added 332 provisional ballots to the vote in 2016 and 578 in 2014.

Lee reported more than 500 provisional ballots Thursday on its election website.

Voters may be required to cast a provisional ballot for a number of reasons, including questions about the correct polling place, a problem with their name missing from a precinct register due to a change of address, or a signature not matching the one in the county’s voter registration record.

If the reason a provisional ballot is in question is because a voter did not provide an acceptable photo and signature identification when appearing to vote at a polling station, the local canvassing board can simply compare the signature on the provisional ballot envelope with the signature on the voter’s registration record.

If the board believes the signatures match, the provisional ballot is counted. Local canvassing boards are made up of the county supervisor of election, a county judge and the chair of the county commissioners.

While there are no specific rules that govern the process of ensuring those signatures match for them to be verified, local election supervisors regularly receive training on that issue.

“My signature is never 100 percent spot on with another one of my signatures, but the J in my first name and the H in my last name is distinctive and always are near identical,” Gulf County Supervisor of Election John Hanlon said. “That’s enough of a match.”

While Hanlon said he can only speak for Gulf County in the Panhandle, a GOP stronghold, he says it is a pretty standard process statewide when reviewing provisional ballots.

“I would say every county is pretty uniform in how they process provisional ballots,” Hanlon said. “I wouldn’t say that any county is more strict or more lenient than another.”

In 2017, local elections assumed responsibility for immediately notifying the voter when a signature is either missing or does not match what is on the voter registration records, said Sarah Revell, a spokesperson for the Florida Department of State.

"If something looks wrong in the provisional ballots, I will call them to ask them to come in with the photo ID with a signature," Hanlon said.

He said there are 10 provisional ballots from the 5,979 total votes cast this election in Gulf County.