On the home turf of his chief Republican rival and in his adopted state, former President Donald J. Trump told a sprawling conservative gathering in Florida on Saturday night that it was futile for Gov. Ron DeSantis to keep battling him for the party’s presidential nomination.
In a prime-time speech at the Turning Point Action Conference in West Palm Beach, Fla., Mr. Trump claimed that his polling lead over Mr. DeSantis and every other G.O.P. candidate was insurmountable, and suggested that the Florida governor should stand down for the good of the party.
Mr. Trump, who leads Mr. DeSantis by roughly 30 percentage points in national polls, dismissed Mr. DeSantis’s early momentum before he officially entered the race in May as a mirage.
“He was never that close, by the way,” Mr. Trump told about 6,000 grass-roots activists at the Palm Beach County Convention Center. Turning Point Action is a political arm of Turning Point USA, a pro-Trump grass-roots group focusing on millennial conservatives that was founded by Charlie Kirk.
Mr. Trump seized on his rival’s absence from the two-day event, which drew about a third of the Republican presidential field as speakers.
“I don’t know why he’s not here,” he said. “He should be here representing himself.”
In a statement on Saturday, Bryan Griffin, the campaign press secretary for Mr. DeSantis, shrugged off Mr. Trump’s criticism.
“Governor DeSantis spent the day with Iowans and spoke to a packed house at the Tennessee G.O.P. Statesman Dinner later that night,” he said. “This was a day after he delivered the strongest interview at the Family Leadership Summit, which Donald Trump notably skipped. Ron DeSantis is campaigning to win.”
Mr. Trump was greeted onstage with pyrotechnics and a nearly three-minute video montage of the former president. While organizers prepared the stage for his entrance, Mr. Trump’s supporters, many in their ubiquitous red caps, watched musical performances of Elvis and Pavarotti on giant screens.
Mr. DeSantis declined an invitation to speak at the end of the conference on Sunday, according to organizers, who noted that he had worked closely with Turning Point Action during the midterm elections last year and took part in several rallies that supported Trump-endorsed candidates.
But on the same day that Mr. DeSantis announced his campaign in May, the conservative group announced that Mr. Trump would headline its conference in Florida, perhaps miffing the host governor.
The lineup of speakers on Saturday may have given Mr. DeSantis further pause. It included three Republican House members from Florida who have endorsed Mr. Trump’s candidacy: Representatives Byron Donalds, Anna Paulina Luna and Matt Gaetz.
In succession, each professed their loyalty to the former president, as booming subwoofers and smoke machines added to the theatrical effect.
Mr. Gaetz, the provocateur who nominated Mr. Trump for House speaker earlier this year during the G.O.P.’s protracted leadership fight, got a roar from the crowd when he said that Mr. Trump’s allies were unflinching.
“Of course, we ride or die with President Donald John Trump,” he said.
And when Megyn Kelly, the former Fox News commentator, dared to suggest at the event that the Republican nominating contest was probably a two-candidate race between Mr. Trump and Mr. DeSantis, several thousand activists booed.
Ms. Kelly, who famously tangled with Mr. Trump in a G.O.P. debate in 2015, relented.
“The vast majority of the Republican Party wants Trump,” she said, adding that Mr. Trump’s indictments had only burnished his stock with conservative voters. “We all know who the best middle-finger candidate is.”
In a nearly 100-minute speech, Mr. Trump noted that Mr. DeSantis had once been his ally and had sought his endorsement in his first race for governor in 2018.
“I got him elected,” he said. “He was dead. He begged me to endorse him.”
Mr. Trump said that he had been taken aback when Mr. DeSantis later declined to say whether he might challenge him for the Republican nomination, using an expletive to refer to the Florida governor.
Tucker Carlson, who was fired from Fox News in April, whipped the audience into a frenzy with an appearance immediately before the former president.
“I don’t think most unemployed people get a reception like that,” Mr. Carlson said.
Mr. Carlson doubled down on his baseless claims that voting machines had been rigged during the 2020 election and expressed sympathy for the Capitol rioters, saying that a country that squashes discussions about the electoral process was not a democracy.
Vivek Ramaswamy, the multimillionaire entrepreneur running for the Republican nomination, also spoke on Saturday. Three other long-shot candidates — Asa Hutchinson, the former governor of Arkansas; Francis X. Suarez, the mayor of Miami; and Perry Johnson, a wealthy businessman from Michigan — are scheduled to speak on Sunday.
So are Stephen K. Bannon, Mr. Trump’s onetime chief strategist who was found guilty of contempt of Congress; and Roger J. Stone Jr., the pro-Trump operative who was convicted of obstruction but had his sentence commuted by Mr. Trump. In the convention center’s lobby, Mr. Stone took selfies with Mr. Trump’s supporters.
“All the cool people are here,” Mr. Carlson said.