AN UNPRECEDENTED war of words between Donald Trump and Mitt Romney, the Republican Party’s nominee for the presidency in 2012, set the tone for the Republican primary debate held on March 3rd at the beloved Fox theatre in Detroit. “His is not the temperament of a stable, thoughtful leader,” said Mr Romney in a speech he gave at the University of Utah on the same day. He called Mr Trump “a phony” who is “playing the American public for suckers”, a man whose “imagination must not be married to real power”. The Republicans’ nominee in 2008 joined in, declaring his “many concerns about Mr Trump’s uninformed and indeed dangerous statements on national-security issues”. John McCain was echoing the worries of dozens of conservative defence and foreign policy officials who had written an open letter asserting that Mr Trump’s “vision of American influence and power in the world is wildly inconsistent and unmoored in principle”. After winning seven of the 11 states at play in Super Tuesday on March 1st, Mr Trump is the undisputed front-runner in a race that has dwindled to just four contenders. Ben Carson, a retired neurosurgeon, all but dropped out on March 2nd, leaving Marco Rubio, Ted Cruz and John Kasich in the arena to fight the real-estate tycoon whose ascent has sent shivers down the spine of the Republican establishment. Belatedly, the GOP’s grandees are putting up a robust defence, which was reflected in a debate that focused largely on Mr Trump. The three Fox News moderators of the debate—including Megyn Kelly, Mr Trump’s nemesis in the network’s first debate of the season—even came up with slides and other props to show how Mr Trump’s fiscal plans don’t add up and how he frequently contradicts himself on foreign policy.

After a week of trading insults and put-downs, Mr Trump and Marco Rubio, a senator from Florida, had expressed the desire to have a proper policy debate. It wasn’t to be; the debate descended into an undignified brawl between angry men. Mr Trump said he was taking back his description of Mr Rubio (whom he otherwise insisted on calling “Little Marco”) as a “lightweight”, but complained about a joke Mr Rubio made about his allegedly small hands. “He referred to my hands,” Mr Trump said, lifting his arms to show them to the audience. “If they’re small, something else must be small. I guarantee you there’s no problem.”

The only candidate who benefited from the sharp descent below the belt was John Kasich, the governor of Ohio, who has largely abstained from personal attacks in all of the 11 Republican primary debates. Coming across as the only adult on the stage, Mr Kasich had possibly his best debate so far. Whenever he talked, the other candidates seemed to be nodding in agreement. The message was his usual mix of common sense with a reminder of his considerable experience in government and his solid record in Ohio. He talked about Ronald Reagan rebuilding the army and pointed out that he worked with him: “I was there. I knew Ronald Reagan.” Going further than Mr Rubio, who said he would send special forces to fight Islamic State, Mr Kasich said a significant American presence on the ground was needed in Syria, Iraq and even Libya, as part of a broad international coalition.

Immigration was again a central topic. Ms Kelly asked Mr Trump about an interview he gave to the New York Times in January, in which he is said to have shown flexibility on some policies, in particular about his proposal to deport more than 11m illegal immigrants. She suggested he had also told the Times that aspects of the much-ridiculed wall he plans to build on America’s southern border might be negotiable—and then challenged Mr Trump to make the audiotape of the interview public. Mr Trump refused Ms Kelly’s offer, though he admitted that on immigration there has to be some “tug and pull and deal”. As for his determination to build the wall, he claimed that he was not very flexible at all.

Mr Cruz’s main contribution to the evening was a barrage of attacks against Mr Trump. He made much of lawsuits filed by former students of the now-defunct Trump University. In one of three pending suits against Mr Trump, the school is accused of “engaging in specific fraudulent, deceptive and illegal acts”. Mr Cruz also enumerated the number of cheques that Mr Trump had written to Hillary Clinton—four in the 2008 presidential race alone—to prove that Mr Trump is not really a conservative. Mr Trump retorted he had made all these donations to the Democrats’ front-runner at the time because it was good for business.

The most comical moments of the evening were provided by Mr Cruz, trying to get Mr Trump to shut up. “Count to ten, Donald,” he advised at one point. At another moment, he said “breathe, breathe, I know, Donald it’s hard, but breathe”, as if to quieten his rival. Mr Rubio wondered whether they could continue the debate when their yoga session was over, to which Mr Cruz replied that he hoped there wouldn’t ever be yoga on stage. “At least he is flexible,” said Mr Rubio about Mr Trump.

Michigan’s and Detroit’s financial troubles made an appearance in the debate, albeit in passing. Mr Rubio said that he respected the state’s governor, Rick Snyder, for having taken responsibility for the scandalous lead-poisoning of the tap water in the city of Flint. Mr Cruz sang praise of Detroit’s past glory as an arsenal of democracy and the Silicon Valley of its day. He blamed 60 years of leftist policies for its subsequent descent into the financial abyss.

However rowdy their exchanges, at the end of the debate the other contenders affirmed that they would back Mr Trump if he were to become their party’s nominee. Mr Kasich added that he would do it even though sometimes Mr Trump made it a bit hard. Asked whether he would support the GOP nominee, Mr Trump raised an eyebrow and asked “If it’s not me?” Then, somewhat hesitantly, he said he would back whoever becomes the nominee.

Mr Trump was the main target of hard questions during the debate and remained on the defensive for most of the evening, yet afterwards he said that he had expected the debate to be much tougher. In spite of the strong headwinds from his party’s establishment, Mr Trump has reason to feel confident. The latest polls from the Detroit Free Press, the city’s leading daily, predict that he will continue his winning streak at the next primary election, on March 8th, when Michigan goes to the polls. Mr Trump has 29% of the state’s expected votes, compared with 19% for Mr Cruz and 18% for Mr Rubio. In a triumph of hope over experience, on March 3rd the Free Press endorsed the man who ought to be regarded as having won the debate: John Kasich.