Despite Trump's insistence to the contrary, cases of election fraud in the U.S. are exceedingly rare, though experts acknowledge that there are some slightly higher fraud risks associated with mail-in balloting when proper security measures are not put in place.

Just last week, Trump floated delaying November’s election until it was safer to do so in person, a suggestion he is not constitutionally empowered to enact. Trump suggested moving Election Day because an influx in mail-in voting, a practice many have advocated to avoid spreading the coronavirus at polling places, would lead to a “rigged” election that would amount to the “greatest election disaster in history.”

On Monday the president claimed the right to issue an executive order pertaining to his concerns about mail-in voting, another legally dubious proposition, and pledged to sue Nevada over its plans to mail ballots to all registered voters. Asked about what authority the president might have to issue an executive order on mail-in voting, White House press secretary Kayleigh McEnany declined to answer.

But the sudden change in heart on mail-in voting in Florida, which McEnany said stemmed from an unidentified court victory regarding voting in the state, comes as polls in Trump’s adopted home state — and a must-win battleground in November — show him trailing former Vice President Joe Biden.

The press secretary referred questions on the Florida legal win to the Trump campaign, which said that the president’s tweet “speaks for itself.”

“What most states call ‘absentee voting’ has long been termed ‘vote-by-mail’ in Florida — it’s been that way for years, and it works,” deputy national press secretary Thea McDonald said in an emailed statement, adding that “President Trump is fighting to make sure every valid vote counts” and denouncing “train wreck primaries” in New York and California, “where we saw Democrats’ rush to implement a faulty universal vote-by-mail system.”

“Wake up folks, Democrats are the people rigging and delaying elections,” McDonald asserted.

Last month, a Democratic super-PAC and other left-leaning groups agreed to drop a voting-related lawsuit against Gov. Ron DeSantis and the Republican Party on the eve of a federal trial, which McDonald pointed to Tuesday. Priorities USA and other groups were seeking to require paid postage on ballots and to push back the deadline for when ballots needed to be received by elections offices in order to still be counted. But state officials agreed to conduct outreach to local election officials and voters to educate them about various aspects of mail-in voting.

The president's shift on mail-in voting also comes as new data indicates the president’s near-daily assault on the practice may backfire on him come November.

Private polling shared with POLITICO this week showed that Republicans have become overwhelmingly concerned about mail balloting. In a state where presidential elections are regularly decided by thin margins, 15 percent of Trump voters in Florida said that getting a ballot in the mail would make them less likely to vote in the fall.

Trump’s assault on mail voting threatens his reelection bidAs of last month, Florida Democrats said they held a 500,000-voter advantage over Republicans in enrollment for mail-in voting, a shift away from the GOP's long-held dominance among absentee ballot-casters. The 500,000-voter gap is more than four times the slim margin by which Trump won Florida in 2016.

Florida has allowed excuse-free mail-in voting since its 2000 election disaster, and in recent years has scrubbed all references to “absentee” voting in state law due to increasing confusion between the two terms. In July, amid Republicans’ push to register its voters to cast their ballot by mail, the party blurred out a portion of one of Trump’s ubiquitous tweets on the issue.

Asked about the shift in a coronavirus briefing Tuesday evening, Trump praised the state’s current and former GOP governors as he asserted that “over a long period of time” the state has handled mail-in ballots “extremely professionally.” Trump would not say what differentiated Florida from the rest of the country, including other states that routinely conduct elections entirely by mail, but he indicated that his concerns lay with states trying to quickly scale up their vote-by-mail operations.

“In the case of Florida, they've done a great job, they've had tremendous success with it, they've made it really terrific. This took years to do. This doesn't take weeks or months,” he said, comparing the state to Nevada, which moved to expand mail-in voting in the last week, and suggesting that the U.S Postal Service was uniquely “built up” in Florida.

Trump has repeatedly issued warnings of chaos surrounding the widespread use of mail-in ballots, pointing to a pair of New York City primaries that have yet to be called more than a month later and a municipal election in New Jersey that saw almost 20 percent of mail-in votes thrown out. Trump has also accused the U.S. Postal Service of being unprepared to handle a surge of mail-in ballots, though the agency rejected that notion on Monday.

McEnany insisted Tuesday that Trump's stance had not changed, and that he was still opposed to so-called universal mail-in voting, where states proactively mail ballots to every registered voter without requiring a request. Several states already conduct their elections entirely by mail, and an analysis last month of voting in three such states found that officials identified an infinitesimal amount of potentially fraudulent ballots.

Florida will be one of 42 states that in November will effectively allow for, at a minimum, no-excuse absentee balloting — meaning any voter, regardless of age, health or location on Election Day, will be able to vote by mail should they choose to do so.

Gary Fineout and Matthew Choi contributed to this report.