The turbo-charged intellect of Newt Gingrich, the former Speaker of the House, powered him to the top of the polls for a spell until voters remembered that he had twice brought the government to a halt in the 1990s and thrice been married.
The late surges of Ron Paul, the libertarian congressman from Texas, and Rick Santorum, a former Pennsylvania senator and conservative cultural warrior, have been well timed. They are likely to occupy two of the top three spots, along with Mitt Romney, whose outstanding virtue as a candidate is that he is none of the above.
Where his rivals have been unpredictable, error-prone and disorganised, Mr Romney has been steady, virtually fault-free and well drilled. He has retained a campaign structure from his failed bid for the nomination in 2008 and has raised much more money than anyone else partly through his Wall Street connections.
His great problem is personality. As one US commentator put it, there is a “dazzle gap” with Mr Romney, a polite way of saying he is rather dull. Even supporters rarely summon a superlative to describe their reasons for backing him. “Solid” and “professional” are words used often.
The more conservative among the party faithful regard him as ideologically dubious, a northeastern liberal sham who will say anything to get elected. Christians are suspicious of his Mormonism, though they are usually too polite to say so.
There were mainstream candidates who seemed stronger than Mr Romney and who flirted with entering the race but were put off by the physical and psychological demands of campaigning non-stop for 18 months. Chris Christie, the overweight and outspoken governor of New Jersey, was among them.
But the party must play the hand it is dealt, which appears to be Mr Romney, and given the extremes and eccentricities of his rivals, his dullness is just what the Republicans need if they want to beat Mr Obama.
As Stephen Hess, a senior fellow at the Brookings Institution, says: “If they choose anyone but Romney it’s political suicide. They are such a collection of very weak candidates.” Matt Bennett, a veteran of Bill Clinton’s White House, confirms that the man from Boston is the candidate the Democratic administration least wants to face.
“Democrats were rejoicing during the Newt Gingrich surge,” he says. “We were giddy with anticipation because he could not win 100 votes” in the 538-member electoral college that determines the presidency.
A Romney stump speech may be the political equivalent of watching paint dry, but his relentless focus on the economy and his own background in the private sector is exactly the right focus during a recession.
“He lacks passion but passion isn’t the issue now,” says Mr Hess, who advised presidents Ford and Carter. “He is a successful businessman, which isn’t a bad thing to be in this climate. The issues will be jobs, jobs, jobs and the election will be fought on the economy and Obama’s record.” As election day in Iowa has approached, more and more Republicans have begun to regard a Romney nomination as something of an inevitability.
Some consider he could have the nomination wrapped up within weeks.
“I think he will win and I think he will make a good president, but he just doesn’t touch people, he just doesn’t come through too well,” says a Rick Perry volunteer among the hundreds who flocked into the state over the weekend to help candidates in the final push for votes.
“Mitt Romney is solid and I think he will be the candidate when all is said and done,” says Mark Lundberg, the Republican chairman in Sioux County. “He has the resources – he has a great family. Some people may not like him but they are much more comfortable with him as president than the current person sitting in the White House.
“He is conservative in most areas, but as Governor of Massachusetts there are some trade-offs you have to make in that state with its liberal legislature.
“Whoever the party chooses, we are up for a fight. There is so little faith in the President now. He wants to turn us into a government-controlled economy, when it was free markets and individual freedom that built our country. We hope this is the beginning of the end of Barack Obama.” Mr Lundberg’s opinion is noteworthy because his county is among the most conservative in the agricultural Midwestern state. Mr Obama was outvoted there in the 2008 presidential election by eight to one.
If the likes of Mr Lundberg are prepared to attribute Mr Romney’s liberal transgressions in Massachusetts to necessary compromise, then the party will probably fall into line behind the former venture capitalist, especially if he wins two out of the first three contests.
Unlike Democrats, who happily let their candidates tear each other apart for months on end – the epic battle between Obama and Hillary Clinton four years ago was only the latest example – Republicans are far more disciplined. In 2008 Senator John McCain was loathed by many conservatives but still had the nomination sewn up by early March.
In Mr Romney, the party could settle on a candidate who can appeal to the independent voters and disaffected Democrats who will decide the next occupant of the White House. But they could also, by default, find a candidate capable of saving the party from itself.
For a year now the Republicans have controlled the House of Representatives, after their numbers were swelled in the 2010 midterms by the Tea Party movement.
Remaining true to a promise to cut spending without raising revenues, they refused to give an inch to Mr Obama during interminable talks and failed deals on the budget and spending. The reaction from much of the public has been negative, with Congress’s approval rating now at an all-time low of nine per cent.
Only recently did the Republicans yield, agreeing to extend a tax break for two months rather than two years. It was a hint that the leadership in Congress is tiring of the Tea Party’s dogmatic approach to deficit reduction. It was confirmation of the fact that they would rather work with someone like Romney, rather than one of the loose cannons aiming for the White House.
Such is the backlash against Washington that Democrats are beginning to hope that in 2012, when the entire House is up for grabs again, they will regain many of the seats lost in the Tea Party tsunami.
“These people are not interested in governing,” says Mr Bennett. “They are Jacobeans, they are revolutionaries and cannot manage the country. Congress has ceased functioning in a rational way, and Americans hate that a big debt deal wasn’t pulled off. Americans want their politicians to behave like adults.” Mitt Romney has his faults, but juvenile behaviour is not among them.