The experience was probably the same whether you were in the "spin-room" adjacent to the university auditorium in Michigan where the rivals were debating or watching on television. It was agonising. For myself, I just knew, even as Rick Perry started his sentence, that the tail-end of it was going to elude him.

Of all the clangers and boobs of the pre-, pre- presidential campaign that has brought us to the eve of the first actual voting in the Republican nomination derby, the failure of Governor Perry to identify the third of the three federal agencies he was vowing to shut down was the most astonishing. It lasted 53 seconds. You can hang yourself comprehensively in 53 seconds.

The remarkable thing is, in spite of the comedy and the errors, nearly all the Republicans who started on this slog for the right to challenge Barack Obama this November, are still standing. True, Tim Pawlenty, former Governor of Minnesota, threw in the towel in August but because of problems with money. Get ready to see others stop in the pits and not reappear.

Credibility did not seem like it would be an issue for Mr Perry. The serving Governor of Texas plunged in late – two days before Mr Pawlenty quit – and seemed to be the most potent challenger to Mitt Romney, the ex-Governor of Massachusetts, who is smoother than an anaesthetist's lance and about as numbing. But it quickly became so. The reviews for his debating skills were bad enough before Michigan.

He was quite wan when, almost by magic, he appeared beside me in the spin-room minutes after the debate was over (candidates generally send surrogates to talk to the likes of us). He made a joke about his Texan boots and stepping in cow poop to send two messages: that he has a sense of humour about himself – he had said "oops" on live TV – and he wasn't about to let one simple brain freeze distract him. Of course the other man who didn't make it this far is Herman Cain – and we miss him. He had an apple pie voice and an irresistible twinkle. Of course, it was that irresistibility that seemingly forced Mr Cain, who once sold pizza slices, to be more gallant than he has allegedly been in the past and to pull out.

Whether or not you believed the allegations of inappropriate behaviour towards women, Mr Cain had a talent for gaffes that would have surely sunk him anyway. He froze one day in November when asked a straightforward question about Mr Obama's policies on Libya. In his fumbling, he almost outdid Mr Perry. In Miami he showed that he knew that Cuban was spoken in Cuba. The worst that Gail Collins, the New York Times columnist, can say about Mr Romney is that he once put the dog on the roof of the car on a family trip to Canada (it's true). But the greatest fear of his handlers is him coming off as elitist. Heaven forefend he is caught windsurfing like the Democratic nominee John Kerry was back in 2004.

Mr Romney is more careful and calculating than his friend from Texas or other candidates. Put him in any political minefield and he will slalom through safely with all the right phrases. Yet his ouch moment eventually came in a debate early in December. He offered to bet Mr Perry $10,000 that something he had just said about his political memoir, No Apology, was incorrect. That's a whole season of windsurfing. Michele Bachmann has established herself as unreliable with the facts among rivals and many voters. How else could she be last now in Iowa, according to most pollsters, when in August she won the state's straw poll? She did it herself with one interview when she tore into Mr Perry for obliging young girls in Texas to be vaccinated for the HPV virus. The vaccine, she said, could cause mental retardation. Medical experts were appalled.

Part of Newt Gingrich's appeal is that he often forsakes slaloming in favour of doing what he wants. In the latter category, he took a Greek cruise with Calista, his wife, last May, prompting a mass exodus of campaign staff who felt he should have been, well, campaigning. He protested that he wanted to see the Greek financial crisis up close (from A Deck, presumably). Probably more toxic to his chances was his blowing off Congressman Paul Ryan's plan on reforming the Medicare programme, calling it the worst kind of "social engineering". Many conservatives still can't forgive him. As for John Huntsman, the former Obama envoy to Beijing and one-time Utah Governor, the clue to his difficulties is before you. His name is Jon, but the 'h' crept on to media badges on the day of his campaign launch before the backdrop of the Statue of Liberty in New York. The press divined at once that his candidacy was "Amateur Hour at the Apollo", an impression he has not been able to correct. There is the other matter of his unwillingness to ingratiate himself to the party's conservative wing like everyone else. Mr Huntsman forgot that there is little place for intellectual integrity in politics.

Money, of course, can cover over the rawest of crevasses. Mr Romney has had some other awkward moments, not least when he appealed to CNN's Anderson Cooper to restore order when he and Mr Perry came close to calling each other names in one of the too numerous debates. And while Mr Pawlenty is gone, it was he who coined the term 'Obamneycare', to tie Mr Romney's reform of healthcare while Governor of Massachusetts to the national healthcare overhaul enacted by Mr Obama so hated by conservatives. But the cash and the backing of the party establishment has helped him ride over all of this.

Mr Perry has cash too. But consider this. In recent weeks he has spoken of the eight justices of the US Supreme Court – every American schoolchild knows there are nine (eight associate justices and one chief justice) – and has dubbed the late Korean dictator, Kim Jong-il, as "Kim Jong the Second". While advocating the quick construction of the so-called Keystone XI pipeline that will link the Canadian oil sands with US refineries on the Gulf Coast, he said: "Every barrel of oil that comes out of those sands in Canada is a barrel of oil we don't have to buy from a foreign source." So the US has absorbed Canada at last.