TALLAHASSEE — Florida is on pace to set a new record for voting by mail in 2016, as nearly one of every four voters will make their choices at home, weeks before Election Day.

As Donald Trump and Hillary Clinton duel in a handful of states and plan for two more TV debates, Floridians are voting in numbers never before seen in a statewide election. At least 2.6 million ballots are flooding mailboxes this week, a figure that could nearly double by Nov. 8, when total turnout could approach 9 million.

"We're seeing it grow and grow and grow," said Polk County Supervisor of Elections Lori Edwards in Bartow.

At the current pace, more than half of all votes in Florida will be cast before the polls open on Election Day. The pacesetter remains Pinellas County, where a larger share of voters vote by mail than anywhere else in the state.

Linda Tindall, 67, a retiree in Seminole, said she wouldn't think of voting any other way.

"There's no expense to the voter, and no travel problems for the elderly," she said. "You have plenty of time to review the ballot in your own home."

Republicans lead Democrats in mail ballot requests, a trend that would appear to favor Trump in the nation's largest swing state.

But Democrats, citing figures from the state, say an aggressive outreach program has closed the gap with the GOP to fewer than 100,000 mail ballot requests.

Democrats also contend that early voters lean toward the candidate with momentum, and at the moment, Clinton holds a slim lead in Florida polls.

The highly volatile race could take unpredictable swings over the next month, but by then, a lot of people in Florida will have already voted by mail.

County election supervisors promote voting by mail as a convenience, and as a hedge against long lines at polling places on election day.

But there's a downside.

Casting a ballot at home requires voters to take simple steps to prevent fraud, yet a surprising number of them get it wrong. As a result, their ballots are not counted.

In the statewide primary on Aug. 30, several thousand ballots were rejected by county canvassing boards because voters neglected to sign their ballot envelope, or because their signature did not match the one on file.

In Jacksonville's Duval County, a three-member canvassing board rejected 669 ballots because of signature problems, including 515 with mismatched signatures.

That's less than one-half of 1 percent of votes cast in Duval in that election, the highest rejection rate of more than a dozen large and medium-size counties the Times/Herald surveyed.

"There are no letters there, just squiggly lines," said Duval Supervisor of Elections Mike Hogan.

Hogan's theory: Voters scribble their name because "they just want to get it done and they're not careful about it."

It's so prevalent that he hired a handwriting expert to teach canvassing board members how to study penmanship.

On social media and on their websites, counties constantly remind voters to sign the envelopes. But the mistakes continue.

The Florida Democratic Party and Democratic National Committee have filed suit against Florida, challenging the law that rejects ballots with mismatched signatures.

Democrats say those voters deserve a second chance to correct any problem, the same as is given to voters who omit a signature completely.

Those voters may be alerted by the elections office and can "cure" a missing signature by submitting a form by 5 p.m. the day before the election. But voters with mismatched signatures have no recourse.

In the primary, Pinellas County rejected 203 ballots, nearly all of them with signature problems. Hillsborough rejected 333 ballots.

The Miami-Dade canvassing board cast aside 594 primary ballots. Broward rejected 774 votes, more than any other county surveyed, including 725 ballots without a signature, according to records provided by election supervisors.

"Rejection rates for vote-by-mail ballots vary significantly across Florida's counties, underscoring the arbitrary and standardless nature of the statewide process," attorney Mark Herron argued in the Democrats' federal lawsuit.

The Bipartisan Policy Center, a nationwide think tank that studies voting trends, said in a research paper in June that the convenience of voting by mail is offset by the risks.

"Voters are more likely to unwittingly disenfranchise themselves," the report said.

The report urged voters to do their homework, including all signature requirements and the deadlines to return ballots.

Tens of thousands more mail ballots are not tabulated every election because they didn't reach elections offices in time.

Both political parties prefer voting by mail in Florida despite the persistent sloppy paperwork problems.

Party strategists have access to the names of voters who have requested ballots and they often "chase" them, using phone calls and direct mail, to remind them to vote.

"There's a huge advantage," said Steve Schale, a Democratic strategist. "You know who has a ballot and who doesn't."

Times researcher Caryn Baird contributed to this report. Contact Steve Bousquet at sbousquet@tampabay.com. Follow @stevebousquet.