Mayor Eric Adams of New York City, his re-election chances in doubt and a federal indictment looming over him, flew to Florida on Thursday to meet with President-elect Donald J. Trump at Mar-a-Lago just four days before the inauguration.

The mayor, a Democrat, made the trip with no advance announcement. His aides said only that the two men would discuss “New Yorkers’ priorities” when they meet on Friday.

Mr. Adams joins a diverse roster of leaders from around the world who’ve made the trip to Mar-a-Lago since the election, and he is not the first Democrat. John Fetterman, the Democratic senator from Pennsylvania, met with Mr. Trump last week. Other recent visitors have included Viktor Orban, the authoritarian prime minister of Hungary, and Justin Trudeau, the liberal prime minister of Canada, who is leaving office soon.

The mayor requested the meeting, according to two people with knowledge of the trip. The city is funding the trip because it has a “city purpose,” the mayor’s spokeswoman said. No other city officials will accompany the mayor, aside from his security detail, she added.

Mr. Trump, who was convicted of 34 felonies in New York City in May, and Mr. Adams have grown publicly closer since Mr. Adams’s indictment in September on five federal corruption charges. It is part of an investigation that the mayor argues is political retribution for his criticism of President Biden’s immigration policies.

Mr. Trump has publicly commiserated with Mr. Adams and seconded his depiction of a Justice Department run amok. Mr. Adams has expressed openness to the notion of receiving a presidential pardon.

While a pardon for Mr. Adams might clear up some legal problems for the mayor, it could also prove politically toxic for an incumbent already facing an uphill path to re-election in a highly competitive June primary in a city dominated by Democrats.

The mayor has drawn criticism from members of his party for appearing to cozy up to Mr. Trump.

But Mr. Adams’s spokesman, Fabien Levy, said the mayor had only the city’s interests in mind. “Mayor Adams has made quite clear his willingness to work with President-elect Trump and his incoming administration on behalf of New Yorkers — and that partnership with the federal government is critical to New York City’s success,” Mr. Levy said.

“The mayor looks forward to having a productive conversation with the incoming president on how we can move our city and country forward,” he added.

A spokesman for Mr. Trump did not immediately respond to a request for comment.

Some of Mr. Adams’s opponents in the upcoming Democratic primary attacked him Thursday night for the Mar-a-Lago trip.

“Eric Adams should state immediately that he will not seek or accept a pardon from Donald Trump,” Brad Lander, the New York City comptroller, said. “New Yorkers deserve to know that their mayor is putting their interests ahead of his own.”

State Assemblyman Zohran Mamdani, also a candidate in the Democratic primary, called the trip “a pathetic and embarrassing gambit by a disgraced mayor to keep himself out of federal prison, nothing more.”

He added, “He’s willing to let our neighbors be deported and our city’s budget be slashed, if it helps him get a pardon from our president.”

“I imagine it’s easier to ask for a pardon in person,” said State Senator Jessica Ramos, who is also running for mayor. She said the mayor’s failure to disclose the trip on his schedule until Thursday night was inappropriate. “It makes New Yorkers feel like he is hiding. ”

Mr. Trump has a famously fraught relationship with New York City. Though he grew up in Queens and later was celebrated for real estate deals and tabloid sizzle, the city resoundingly rejected his first bid for the presidency, and New Yorkers responded to his election in 2016 by stripping his name from several high-rise buildings. Mr. Trump, in turn, took every opportunity to disparage New York.

In 2019, he complained of his treatment at the hands of New York’s leaders and changed his primary residence from Manhattan to Palm Beach, Fla.

In the 2024, New York City voters also rejected Mr. Trump’s presidential bid, albeit by smaller margins. And New York City’s mayor has adopted a far more conciliatory tone.

For months, Mr. Adams has adopted a warm posture toward the incoming president.

In the run-up to the November election, his apparent reluctance to criticize Mr. Trump and to endorse Kamala Harris for president raised questions about whom he intended to vote for. On Election Day, he told reporters he did in fact plan to vote for Ms. Harris.

Since Mr. Trump’s victory, Mr. Adams, who was for a period of time in the 1990s a registered Republican, has repeatedly said he wanted to work with the president-elect, not war with him.

During an interview in December, he did not immediately rule out running for re-election as a Republican, only to later clarify that he did in fact intend to run as a Democrat again.

The same month, he met with Mr. Trump’s incoming “border czar,” Thomas D. Homan, and said they shared “the same desire” to go after undocumented immigrants who had committed crimes in the city. Mr. Homan, who played a central role in Mr. Trump’s first-term family separation policies, proceeded to go on the TV show “Dr. Phil” and praise the mayor.

Around the same time, two of Mr. Adams’s advisers were quietly trying to secure a ticket for him to attend Mr. Trump’s inauguration in Washington on Monday.

At a charity event in September, Mr. Trump said he felt a kinship with Mr. Adams.

“We were persecuted, Eric,” Mr. Trump said at the Alfred E. Smith Memorial Foundation Dinner. “I was persecuted, and so are you, Eric.”

At a news conference three months later, Mr. Trump said he would consider a pardon for Mr. Adams.

William K. Rashbaum contributed reporting.