Just a number of months in the past, the Republican presidential major appeared as if it’d embody a frank and vigorous debate in regards to the management and limitations of Donald J. Trump.

But any urge for food for criticism of Mr. Trump amongst Republicans has almost evaporated in a really brief time. Voters rallied round him after his legal indictment in March on prices associated to hush cash for a porn star, and potential rivals have faltered, with few keen to take direct goal on the former president and front-runner for the nomination.

In a live town hall on CNN on Wednesday, the cheers for each falsehood and insult that Mr. Trump uttered underneath powerful questioning by a moderator confirmed there was little to no daylight between Mr. Trump and the Republican base. A unusual effort to disrupt the love-in by Chris Christie — a possible rival who purchased Facebook adverts to provide viewers members with skeptical questions resembling “Why are you afraid of debating?” — went nowhere.

In surveys and focus groups, a justifiable share of Republican voters say that they would favor a much less polarizing, extra electable nominee. But a close to taboo in opposition to criticizing Mr. Trump has made it exhausting for rivals, other than Mr. Christie and one or two others close to the underside of polls, to face out.

In what seems to be like a rerun of the 2016 Republican major, virtually none of Mr. Trump’s rivals have overtly gone after him, regardless of his obvious vulnerabilities. Instead, they’re hoping — now as then — that he’ll one way or the other self-destruct, leaving them to inherit his voters.

After a jury found Mr. Trump liable for sexual abuse and defamation of the author E. Jean Carroll on Tuesday, Mike Pence, the previous vice chairman, who’s weighing a 2024 marketing campaign, declined to criticize Mr. Trump. In an interview with NBC News, Mr. Pence mentioned it was “just one more story focusing on my former running mate that I know is a great fascination to members of the national media, but I just don’t think it’s where the American people are focused.”

Other 2024 candidates both defended Mr. Trump, such because the entrepreneur Vivek Ramaswamy, or performed down the decision, including Nikki Haley, the previous South Carolina governor. Ms. Haley, who announced her candidacy in February, even defended Mr. Trump this week for threatening to skip Republican major debates. “With the numbers he has now, why would he go get on a debate stage and risk that?” she said.

Only two 2024 hopefuls discovered the decision within the Carroll case to be disqualifying for a would-be president: Mr. Christie and Asa Hutchinson, the previous Arkansas governor. Mr. Hutchinson criticized Mr. Trump’s “contempt for the rule of law.”

Several months in the past, polling had suggested Mr. Trump may very well be a doubtlessly weak candidate, with solely 25 to 35 % assist from Republican voters in high-quality surveys. The Republican National Committee promised an autopsy of the 2022 midterms that was anticipated to handle Mr. Trump’s function within the social gathering’s shocking losses.

But at this time, the lane within the Republican major for a candidate who’s overtly vital of Mr. Trump appears to be closing.

Mr. Hutchinson’s long-shot marketing campaign has failed to realize discover. Mr. Christie, the previous governor of New Jersey, who has promised a choice this month on whether or not he’ll run, additionally has but to generate a lot curiosity. Even the sometimes vital Mr. Pence, who mildly prompt Mr. Trump can be “accountable” to historical past for the Jan. 6 assault on the Capitol, is struggling for affirmation from the Republican base.

And the R.N.C. post-mortem of the midterms? A draft reportedly didn’t point out Mr. Trump in any respect.

David Kochel, a Republican strategist who suggested Jeb Bush when he ran in opposition to Mr. Trump in 2016, mentioned there was no alternative for a candidate overtly vital of Mr. Trump within the 2024 major.

“Voters have seen Trump as the most attacked president of their lifetimes, and they have an allergic reaction to one of their own doing it,” Mr. Kochel mentioned. “He’s built up these incredible antibodies, in part stemming from how the base perceives he has been treated.”

A CBS News poll launched this month discovered that amongst seemingly Republican major voters, solely an insignificant handful, 7 %, needed a candidate who “criticizes Trump.”

The three candidates whom voters are the least open to contemplating, the survey discovered, are those that have criticized Mr. Trump to various levels: Mr. Christie, Mr. Hutchinson and Mr. Pence.

David Carney, a Republican strategist in New Hampshire, mentioned he had anticipated the race to be extra aggressive by now, however a turning level occurred in March with Mr. Trump’s indictment in New York.

“It fell into the president’s narrative of the past five years,” Mr. Carney mentioned, referring to Mr. Trump’s portrayal of himself as a sufferer of a legal justice system out to get him. Mr. Carney described what he referred to as a “boomerang” impact on Republican major polls. “They’re beating up your guy — there’s a rallying around the flag.”

Mr. Trump’s rivals might nonetheless see a surge in assist between now and subsequent yr’s first major contests, however in the intervening time he’s dominating all challengers. A polling average exhibits him with a 30-point lead over his closest rival, Gov. Ron DeSantis of Florida, who has but to formally announce his run. All different candidates, declared and potential, are distant afterthoughts within the race, for now.

The former president is insulated from criticism, strategists mentioned, due to the extraordinary and dug-in partisanship of the Republican base, and since a lot of these voters get info solely from right-wing sources, which have minimized the Jan. 6 assault and obscured Mr. Trump’s 2020 loss.

“They barely have access to the truth,” mentioned Sarah Longwell, an anti-Trump Republican strategist. Ms. Longwell, who hosts a podcast about Republican voters referred to as “The Focus Group,” mentioned a large share of major voters needed to maneuver on from Mr. Trump.

But according to polling, a majority of Republican voters don’t imagine Mr. Trump actually misplaced in 2020. “Every politician on their team, everyone they know and all the media they consume — all tells them that the election was stolen,” Ms. Longwell mentioned.

Mr. Christie, probably the most sharply vital 2024 hopeful of Mr. Trump, lately attacked the previous president, calling him “a child” for denying the 2020 election outcomes and cowardly for suggesting he would possibly duck Republican debates.

But when Mr. Christie examined the electoral waters throughout visits to New Hampshire the previous two months, together with on the similar faculty the place Mr. Trump’s city corridor came about on Wednesday, his crowds appeared tilted towards independents and even Democrats, together with those that knew him as the home conservative on ABC News.

One aspect that will think about Mr. Christie’s calculus: The New Hampshire major subsequent yr might favor an anti-Trump Republican due to an inflow of unbiased voters. Because Democrats selected South Carolina as their first nominating state — and since President Biden may not appear on the New Hampshire ballot or marketing campaign within the state — as much as 100,000 independents are anticipated to forged ballots within the Republican race, the place they might tilt the outcomes.

“Independents are open to voting for a Republican candidate,” mentioned Matt Mowers, who served as Mr. Christie’s New Hampshire state director in 2016, “but they aren’t open to voting for a crazy Republican.”