Mr. Trump has another asymmetrical advantage: Current and potential rivals have sought to avoid criticizing him too harshly so as not to alienate Republicans who still like Mr. Trump and are automatically suspicious of anyone attacking him. By contrast, other 2024 contenders have shown no hesitation in going after Mr. DeSantis.

“His team — maybe him — is excellent at manufacturing the veneer of courage without actually delivering on the real thing,” Mr. Ramaswamy said in an interview last month. “And that can work across TV and even social media,” he added. “But once you poke a little bit, it’s like a little bubble in the air: A little touch, and it’s burst.”

Mr. Ramaswamy, who has criticized Mr. Trump, has aimed most of his fire at Mr. DeSantis. A close friend of Mr. Trump’s son-in-law, Jared Kushner, Mr. Ramaswamy dined with Mr. Trump and Mr. Kushner at the former president’s New Jersey club, Bedminster, in 2021, according to two people familiar with the event.

And while the field grows, there is the matter of the debate stage, where Mr. Trump eviscerated his opponents in the 2016 primary.

The chair of the Republican National Committee, Ronna McDaniel, said earlier this year that she did not expect to need two debate stages as the party required in 2016, with the tiers of candidates determined by polling.

But there could be as many as a dozen declared candidates by August, and many are already racing to collect the 40,000 donors and 1 percent polling threshold the party has indicated will be needed to get onstage. This pool includes longer-shot candidates like Larry Elder, the talk radio host who got walloped in the California recall election.

“Everyone says, ‘We have to keep people from getting in.’” Mr. Sununu said. “That’s the wrong message, the wrong mentality, and that’s not going to work.”

But he acknowledged that consolidation will eventually be needed to defeat Mr. Trump.

“The discipline,” Mr. Sununu added, “is getting out.”