In an abrupt reversal, President Donald Trump is encouraging voters in the critical swing state of Florida to vote by mail after months of criticizing the practice — and while his campaign and the GOP challenge Nevada over its new vote-by-mail law.

Democratic requests to vote by mail have surged in Florida, a state that Trump almost certainly must win to secure a second term. Democrats currently have about 1.9 million Floridians signed up to vote by mail this November, almost 600,000 more than the Republicans’ 1.3 million, according to the Florida secretary of state.

In 2016, both sides had about 1.3 million signed up before the general election.

“Whether you call it Vote by Mail or Absentee Voting, in Florida the election system is Safe and Secure, Tried and True,” Trump tweeted Tuesday. “Florida’s Voting system has been cleaned up (we defeated Democrats attempts at change), so in Florida I encourage all to request a Ballot & Vote by Mail!”

White House press secretary Kayleigh McEnany rejected the notion that the Republican president has changed his views. She said Trump supports absentee voting by mail for a reason, as opposed to states mailing out ballots to all voters regardless of whether they requested them. Most election officials say there is little effective difference between absentee voting and voting by mail.

Trump elaborated Tuesday on why he supports voting by mail in Florida but not elsewhere.

“They’ve been doing this over many years, and they’ve made it really terrific,” he said during a news conference.

“This took years to do,” he added. “This doesn’t take weeks or months. In the case of Nevada, they’re going to be voting in a matter of weeks. And you can’t do that.”

Nevada officials joined several states that plan on automatically sending voters mail ballots. Two states, California and Vermont, moved earlier this summer to adopt automatic mail ballot policies.

With the bill passed by lawmakers on Sunday, Nevada Gov. Steve Sisolak, a Democrat, signed it into law on Monday. In a tweet Trump called the bill’s passage “an illegal late night coup” and accused Sisolak of exploiting the coronavirus pandemic to ensure votes would favor Democrats.

Making good on Trump’s threat of legal action, his campaign and the national and state GOP filed suit Tuesday in U.S. District Court in Nevada against the secretary of state to stop the plan. Contending the new law would undermine the election’s integrity, the suit included the argument that Nevada would violate federal and constitutional law by requiring election officials to accept and count ballots received after Election Day even when those ballots lacked objective evidence that they were cast on or before that day.

Trump’s praise of its voting aside, Florida hardly has a history of flawless elections, most notably in 2000, when the state’s disputed vote count had to be resolved by the U.S. Supreme Court, delivering the presidency to Republican George W. Bush over Democrat Al Gore.

Trump cited a New York race as an example of what can go wrong, claiming no one could know the winner. In that race, a judge ruled Monday that about 1,000 disputed ballots should be counted. That will likely not affect the outcome since the incumbent, longtime Democratic Rep. Carolyn Maloney, is leading her closest challenger by about 3,700 votes.

“I think they have to do the election over,” Trump said. “That election is no good.”

More voters during this year’s primary elections opted to vote by mail, and several states relaxed restrictions for voting absentee through the mail. Trump himself voted by mail in the Florida primary this year.

Five states have relied on mail-in ballots since even before the coronavirus pandemic raised concerns about voting in person, but there is no evidence to support Trump’s assertion that voting by mail leads to widespread fraud.

Trump has gone so far as to suggest by tweet that the November election should be delayed “until people can properly, securely and safely vote.”

States that use mail-in votes exclusively say they have necessary safeguards in place to ensure that a hostile foreign actor doesn’t disrupt the vote. Election security experts say voter fraud is rare in all forms of balloting, including by mail.

With Florida’s large retirement population, voting by mail is expected to become a more popular option this November. Sen. Marco Rubio, R-Fla., was asked Saturday if he had concerns about the option. “No, I’m not concerned about mail-in voting in Florida,” he said tersely.

Florida GOP officials welcomed Trump’s tweet.

“Thank you for the clarification Mr President! This is very helpful,” said Joe Gruters, the chair of Florida’s Republican Party. “Florida will deliver you the 29 electoral votes!”

Florida’s presidential contests are usually close, with Trump winning by just 1.2 percentage points in 2016 and George W. Bush winning by just 537 votes in 2000.