Florida Used to Be a Swing State. Now Democrats Can Only Cling to Glimmers of Hope.

Donald J. Trump and Ron DeSantis remade Florida into the red-hot center of the Republican universe, transforming the state into a bastion of power for their party.

But now, recent surveys showing a tightening presidential race in Florida have given some Democrats glimmers of hope that they could begin to claw their way back into contention in what was once the most contested of all the battleground states.

That movement in public opinion, along with the announcement that Robert F. Kennedy Jr. will appear on the ballot in Florida this fall, has injected a fresh sense of unpredictability into the wild world of the state’s politics. And yet some Democrats are engaging in a kind of political magical thinking, flirting with the notion that small signs of improvements mean the state could turn toward their party once again. The reality is much more sobering: Wresting Florida from Republicans’ grip in key races will be difficult.

Some Democrats see opportunity in state ballot measures that would enshrine abortion rights and legalize marijuana for recreational use, and believe that both issues could boost liberal turnout in November. Others point to President Biden’s growing advantage with seniors, a key demographic group in the state, and to polling that shows Senator Rick Scott, a Republican, facing an increasingly competitive re-election contest.

“Florida is a very tough state for Democrats to win,” said Dan Kanninen, the Biden campaign’s battleground states director. “We know that with eyes wide open, but there are some particular factors this time around that make Florida much more interesting.”

Politically interesting is far from politically competitive. Even with Mr. Kennedy on the ballot, Republicans and Democrats say that his presence is unlikely to be decisive.

Mr. Trump won the state twice, nearly tripling his margin of victory to three percentage points in 2020. Two years later, Republicans swept the state in the midterms, with Mr. DeSantis winning with the largest margin by a Republican candidate for governor in modern Florida history.

Since then, any evidence of a Democratic comeback has been limited to the smallest of bright spots for the party. Last year, Democrats won an upset mayoral race in Jacksonville, Florida’s biggest city. In January, Democrats flipped a Republican statehouse seat near Orlando with a focus on abortion rights.

Democrats have found additional sources of optimism in recent polling. A survey by Florida Atlantic University released last week showed Mr. Trump with a six-point lead among likely voters, a drop from his nine-point advantage in April. Polls conducted earlier this spring found Mr. Trump with as much as a 15-point advantage. The latest poll had a Democratic-leaning sample that many Florida political observers found unrealistic.

The same survey showed Mr. Scott with a narrow two-point lead over former Representative Debbie Mucarsel-Powell, a dramatic shift from his 17-point advantage in April. She remains unknown among many voters. Mr. Scott is much better known but has notched only narrow electoral victories. His personal wealth, however, has helped him dominate the airwaves.

Party officials in the state believe they can ride opposition to some of Mr. DeSantis’s controversial policies, including a parental rights law that critics nicknamed “Don’t Say Gay,” his expansion of gun rights and his public feud with Disney, the state’s largest private employer.

On Saturday, the state Democratic Party announced that it had candidates contesting every state legislative seat for the first time in three decades — a recruiting win that the party attributed to pushback against conservative “extremism.”

“It’s a record-breaking accomplishment for the Florida Democratic Party and a stark contrast to the party we inherited after 2022 — a party Republicans declared ‘dead’ just one year ago,” Nikki Fried, the party chairwoman, said. “Now, we have the momentum.”

Few Democrats deny that they are facing significant structural disadvantages: a moribund Democratic state party, a deep disadvantage in voter registrations and continued disinvestment from the national party. Some Democratic strategists in the state say that the chatter amounts to little more than a head fake.

“It’s a state that both sides want you to think is in play, but in reality, it’s not,” Fernand R. Amandi, a Democratic pollster in Miami, said. “We will be able to safely say that Florida is a swing state again after Democrats win multiple statewide elections.”

Mr. Trump’s campaign has deep relations with the Republican Party of Florida and is led by Susie Wiles, one of the most successful political operatives in the state. Campaign officials say that they are not worried about either ballot measure shifting the composition of the electorate against them. Brian Hughes, a senior adviser to the Trump campaign in Florida, predicted that Mr. Trump would drive his own “substantial” conservative turnout.

He said that Mr. Trump had expanded the base of support that he attracted in 2020, when he won the state by the largest margin for a presidential candidate since George W. Bush in 2004.

“We’re enjoying growth in what is typically seen as not a conventionally Republican base,” he said. “Young voters, Black voters, Hispanic voters.”

In recent weeks, the Biden campaign has expanded its Florida presence, opening three offices, with plans to expand to a dozen by summer’s end. Both the president and vice president have made appearances in the state, hammering Mr. Trump for Florida’s six-week abortion ban.

The Biden campaign’s Florida operation pales in comparison to the tens of millions of dollars the campaign is spending in battleground states. In total, Mr. Biden and allied Democratic groups have spent $328,000 on television ads in Florida this year, a minuscule amount in such a large state. That total was a fraction of the $33 million spent on ads in Arizona and $47 million in Michigan, according to AdImpact, the ad tracking firm.

Much of Mr. Biden’s hopes rest on the two amendments, particularly the abortion referendum. Florida’s ban is more restrictive than what polling shows most voters, including many Republicans, support.

In all seven states where abortion has been put directly to voters since the Supreme Court overturned Roe v. Wade, the abortion-rights side has won. In Michigan, the measure also fueled a surge in liberal turnout, which helped lift Democratic candidates to midterm victories.

Still, Michigan may not offer many harbingers for Florida. Since 2012, Florida voter registrations have shifted so dramatically that Republicans who 12 years ago ran a deficit of about half a million voters are now nearly one million voters ahead.

“The headwinds for the marijuana and abortion amendments — and for any candidate that’s not a Republican — is simple math,” said Nick Iarossi, a lobbyist and longtime supporter of Mr. DeSantis. “When Democrats are dealing with a million more registered Republicans, proportionally the math doesn’t work in their favor.”

Both measures will need significant bipartisan support for passage, given the 60 percent approval threshold required for constitutional amendments in the state. Organizers for Yes on 4 Florida, the abortion amendment campaign, say that they are solely focused on building a diverse coalition — and not on Democratic politics.

“We have the 60-percent threshold that we have to make, and that’s going to take folks that are going to vote for all kinds of candidates on the ballot in November,” Natasha Sutherland, the campaign’s communications director, said.

The abortion ballot questions approved in other states came before voters in off-year or midterm elections, and only in two of those states — the liberal bastions of California and Vermont — did the support surpass 60 percent.

“Nobody is trying to say that abortion doesn’t animate their base to turn out — we’ve seen that everywhere,” said Ryan Tyson, a Republican pollster based in Florida. “However, we haven’t seen them turn out voters that wouldn’t have already turned out, like in a presidential year.”

But Florida voters have backed past liberal-leaning ballot measures while also electing Republicans. The Florida G.O.P. has come out against both amendments. Last month, Mr. DeSantis created a political campaign committee to help defeat both measures.

Some Democrats, who say that Florida has become exponentially more Republican, worry that failure by their leaders to set realistic expectations will lead to further demoralization after a tough Election Day. The only question, those Democrats say, is by how much Mr. Trump and Mr. Scott will improve their victory margins from previous elections.

Mr. DeSantis appears to agree: “Florida is a Republican state,” he said, as he discussed his new political campaign committee last week. “It used to be a swing state. Not anymore.”