Former President Donald J. Trump used a campaign rally on Thursday in New Hampshire to bolster his arguments that it was not worth his time to debate his rivals for the Republican presidential nomination, casting himself as the party’s undeclared nominee.
Standing in front of several hundred supporters in a New England state that was a springboard for his election in 2016, Mr. Trump said that he held a commanding polling advantage in the 2024 Republican primary, months before any voting would begin. He has been posting similar themes on his social media site, Truth Social.
He said that giving his G.O.P. rivals, like Gov. Ron DeSantis, an opening on a debate stage made no sense.
“Why would you do that?” he told the crowd at a DoubleTree hotel in Manchester. In 2019, then as president, he considered skipping any presidential debates for the 2020 race before ultimately debating the Democrats’ nominee, Joseph R. Biden Jr.
And on Thursday he jumped straight to the general election, saying, “I do look forward to the debate with Joe.”
Mr. Biden declared on Tuesday that he would seek a second term. His predecessor claimed at his rally, without evidence, that the video Mr. Biden released to announce his re-election campaign “took supposedly seven takes to get it right.” The video features a montage of scenes from Mr. Biden’s presidency and only a few short clips where he spoke to the camera.
Citing a recent Emerson College poll, Mr. Trump noted that 62 percent of G.O.P. primary voters indicated that they would support him, compared with 16 percent for Mr. DeSantis, who has not yet declared his candidacy. No other Republican was in double digits.
“He’s crashing and burning,” Mr. Trump said of Mr. DeSantis, suggesting that he had benefited in the past from his association with Mr. Trump but that he was now struggling to get a foothold on his own.
Mr. Trump has never shied away from broadsides against other Republicans, something Ronald Reagan famously frowned upon in what became known as the 11th Commandment. And in New Hampshire, Reagan’s presidential library was a target for Mr. Trump, who questioned its selection as the venue for the second G.O.P. primary debate. He pointed out that Frederick J. Ryan Jr., the publisher and chief executive of The Washington Post, another frequent Trump target, was chairman of the Ronald Reagan Presidential Foundation & Institute.
Representatives for the institute did not immediately respond to requests for comment, and The Post declined to comment.
Separately on Thursday in Manhattan, lawyers for Mr. Trump appeared in a federal courtroom to defend him in a case brought by E. Jean Carroll, a former magazine columnist, who has accused Mr. Trump of raping her nearly three decades ago.
Mr. Trump, who has denied the accusation, avoided mentioning the trial during the rally. However, he bemoaned his various other legal entanglements and alluded to his indictment this month by a New York grand jury on charges that he had concealed hush-money payments to a former porn star.
He faces further legal peril. A federal investigation, in the hands of a special counsel, is investigating Mr. Trump’s efforts to reverse his defeat at the polls in 2020 and also his role in the events that led to the storming of the Capitol by his supporters on Jan. 6, 2021. And a Georgia prosecutor is in the final stages of an investigation into Mr. Trump’s attempts to reverse the election results in that state.
While Mr. Trump has opened up a polling lead, the Republican field is fluid and appears likely to expand. It includes Nikki Haley, a former South Carolina governor and a United Nations ambassador in the Trump administration; Asa Hutchinson, the former governor of Arkansas; and the entrepreneur Vivek Ramaswamy.
Another Republican who is entertaining a run is New Hampshire’s governor, Chris Sununu, who recently said that Mr. Trump’s losing streak could continue in 2024. He has cited Mr. Trump’s defeat in 2020 and Republican midterm losses in 2018 and 2022.
Mr. Trump bristled at G.O.P. skeptics, singling out Mr. Sununu, whose name elicited boos from the crowd.
“Isn’t he a nasty guy?” Mr. Trump said, criticizing Mr. Sununu’s decision to run for re-election as governor instead of for Senate during last year’s midterm elections.
Mr. Sununu’s office did not immediately respond to a request for comment.