Candidate after candidate at an Iowa Republican dinner on Friday avoided so much as mentioning the dominant front-runner in the race, former President Donald J. Trump.

But when Mr. Trump took the stage after more than two hours of speeches by his lower-polling rivals, it took him less than three minutes to unleash his first direct attack of the night on his leading challenger, Gov. Ron DeSantis of Florida.

Mr. Trump not only suggested that Mr. DeSantis was an “establishment globalist” but called him “DeSanctis,” which in Mr. Trump’s argot is short for the demeaning nickname DeSanctimonious and is so well-known that most attendees clearly got the reference. “I wouldn’t take a chance on that one,” Mr. Trump joked.

The crowd of more than 1,200, which had warmly welcomed Mr. DeSantis when he spoke earlier, laughed and applauded throughout Mr. Trump’s riffs.

In contrast, Mr. DeSantis hadn’t mentioned the former president at all. The one speaker who did criticize Mr. Trump at length, former Representative Will Hurd of Texas — who is so far from contention that he’s not even attempting to qualify for the first Republican debate next month — was booed off the stage.

The dinner served as yet another reminder of Mr. Trump’s hold over Republican voters, despite his loss in 2020, the party’s struggles in the 2022 midterms and the weighty criminal charges he faces.

Hosted by the Republican Party of Iowa, the event brought together 13 candidates for the nomination, from Mr. Trump to challengers like Mr. DeSantis, Sen. Tim Scott of South Carolina and former Gov. Nikki Haley of South Carolina. Also appearing were former Vice President Mike Pence, the entrepreneur Vivek Ramaswamy and long shots such as the media commentator Larry Elder, who, in keeping with the general theme of the evening, referred to himself as a “Trump clone.”

Each candidate spoke for 10 minutes to attendees at an event center in Des Moines, with Mr. Trump the last to appear. Organizers had said they would cut off the microphone of anyone who went over the time limit.

They proved as good as their word when the evening’s second speaker, former Gov. Asa Hutchinson of Arkansas, breached the 10-minute mark and had to deliver the final words of his speech to a dead microphone with the country song “Only in America” playing loudly over him. (Mr. Hutchinson is polling at around 1 percent.)

As the race takes shape five months ahead of the crucial Iowa caucuses, Mr. Trump is surging ahead of a fractured field of rivals who are largely reluctant to criticize him, cowed by his fiercely loyal base.

But Mr. Trump’s legal troubles could still provide an opening for one of his rivals. The former president has now been indicted twice, and major new charges were added to one of those cases on Thursday. He also is expected to face two additional criminal cases. So far, however, the charges against him have seemed to coalesce Republican voters around his candidacy At the dinner, only Mr. Hurd, a former C.I.A. officer, most pointedly mentioned the charges, and he also contradicted Mr. Trump’s false assertion that he had won the 2020 election.

“One of the things we need in our elected leaders is for them to tell the truth, even if it’s unpopular,” Mr. Hurd said. “Donald Trump is not running to make America great again. Donald Trump is not running for president to represent the people that voted for him in 2016 or 2020. Donald Trump us running to stay out of prison.”

The vast majority of the crowd did not agree. Boos rang out, and some attendees clattered their silverware to drown him out, a stark illustration of the risks of going after the former president.

“Thank you, Will,” said the next speaker, Mayor Francis Suarez of Miami. “You just made it very easy for me.”

Still, some voters said they had appreciated Mr. Hurd’s willingness to walk into the lion’s den.

“I honestly think that it took a lot of courage to say what he said about Trump at the end of there,” said Caden Mohr, 19, an educator from Eagle Grove, Iowa, who is leaning toward supporting Mr. Trump.

But beyond that tense moment, even veiled references to Mr. Trump were rare.

In one instance, Mr. Pence, who served as Mr. Trump’s vice president but fell out with him — and his base — over the Jan. 6 storming of the Capitol, warned voters to “resist the politics of personality and the siren song of populism unmoored from conservative values.”

If anyone is to stop Mr. Trump’s growing momentum, it may have to happen in Iowa, where Mr. Trump has feuded with the popular Gov. Kim Reynolds, a Republican who received a standing ovation when her name was mentioned by another speaker for the first time. Mr. Trump has also skipped events held by influential evangelical Christian leaders.

Mr. DeSantis, in particular, has sought to capture the state’s evangelical voting bloc, running to Mr. Trump’s right on social issues and hitting him on his past support for gay rights. After fund-raising struggles and staff layoffs, Mr. DeSantis chose to begin a “reset” of his campaign with an Iowa bus tour this week.

“We’re doing all 99 counties in Iowa,” Mr. DeSantis told the crowd, which gave him a deafening standing ovation as he concluded his remarks. “You’ve got to go meet the folks, so you’ll see me everywhere.”

But Mr. Trump continues to hold a commanding lead in Iowa polls. A recent survey by Fox Business showed him leading the field with 46 percent of the vote, followed by Mr. DeSantis at 16 percent and Mr. Scott at 11. This week, Mr. DeSantis and Mr. Scott tussled over how the history of slavery is taught in Florida schools, as Mr. Scott seeks to supplant Mr. DeSantis as the leading alternative to the former president.

Of the major Republican candidates, only Chris Christie, the former governor of New Jersey, declined to attend the G.O.P. dinner on Friday. Mr. Christie has said he is not competing in Iowa, pinning his hopes on New Hampshire and South Carolina.

Also appearing at the dinner were Gov. Doug Burgum of North Dakota, the pastor Ryan Binkley and the businessman Perry Johnson.

The crowd’s attention clearly drifted depending on the speaker.

When Mr. Johnson mounted the stage an hour into the dinner, dozens of attendees left their tables, presumably to visit the bar or use the bathroom.

One of the biggest standing ovations of the night was saved for Mr. Ramaswamy, a wealthy political newcomer who is campaigning aggressively in the early nominating states and on Friday promised that he stands for “revolution,” not reform.

Teresa and David Hoover, a married couple from Marshalltown, Iowa, emerged captivated by Mr. Ramaswamy, saying he had a unique message for reaching future generations.

“When we talk to our kids and our grandkids, he’s right on the money — they’re lost,” Ms. Hoover, 65, said. “They need to know what it means to be Americans again.”

After the speeches, the campaigns hosted guests in hospitality suites.

In Mr. DeSantis’s suite, staffers for his super PAC set up pyramids of cans of Bud Light, a company the governor has attacked for a marketing campaign that featured a transgender social media influencer.

The beers weren’t for drinking. Instead, guests were offered buckets of baseballs to hurl at them.

Ruth Igielnik contributed reporting.