The contest for the Republican party's presidential nomination is starting to resemble the old joke about how bureaucrats like to play musical chairs: when the music stops, they put in another chair.

Instead of steadily eliminating hopefuls from contention, as the staggered primary season has done for the past 30 years, each Republican contest so far this curious election year has expanded the field of potential nominees.

On Tuesday the voters of Michigan provided a much-needed seat back in the game for Mitt Romney, who had been staring at potential elimination. He became the third different winner of the first three seriously contested Republican primaries, following Mike Huckabee in Iowa two weeks ago and John McCain in New Hampshire last week.

And it could well be that Mr Romney's surprisingly comfortable win over Mr McCain provided a lifeline not only for him, but for another candidate who hasn't even managed a third-place finish so far — Rudy Giuliani.

With scant support among the small early-voting states, Mr Giuliani staked all on a strong showing in Florida — the first really big state to vote — on January 29. But that gambit would work only in the unlikely event that no one emerged from the first few contests with serious momentum.

The next primary takes place in South Carolina on Saturday, but barring a large victory for one of the frontrunners there — Mr McCain or Mr Huckabee — which looks unlikely, it appears that the Giuliani gambit might have succeeded. The candidates will head to Florida in what polls suggest is a four-horse race. That does not, of course, mean that Mr Giuliani will win — the political obstacles to his candidacy may still be too large. But it does mean that he is much more of a serious contender than he seemed two weeks ago.

For those who care less about the identity of the man who wins the Republican nomination and more about what kind of party emerges from this epic struggle, the Michigan result was not encouraging. Mr Romney won the state with a message of economic interventionism that would have made Gordon Brown blush.

Michigan has been pummelled by the forces of globalisation in the past decade. Tens of thousands of motor industry jobs have been lost to overseas manufacturers of lower-cost, more fuel-efficient vehicles. Mr McCain bravely, but foolishly, sought to tell the voters that most of those jobs were not coming back. Mr Romney did not feel bound by the constraints that such honesty places on a candidate. Telling voters that “cars are in my blood” (at least he didn't say gasoline), he pledged that as president he would roll up his sleeves and force the federal government to save the industry.

It was another remarkable redesign of the Romney model in the space of just a few months.

A long, long time ago — last summer, to be precise — Mr Romney was campaigning as a kind of super-technocrat: a successful businessman and former governor with a record for getting things done. When that didn't seem to rock the voters, he turned himself into a social conservative, breathing religious fire and promising to deport every last one of America's 12 million illegal immigrants.

When he lost that battle in Iowa to the Baptist preacher Mr Huckabee, he told the voters of New Hampshire that he was an agent of change — a kind of Barack Obama in a different-coloured skin. When that failed, he headed to Michigan, as the agent of a failed 1970s industrial policy.

Mr Romney, in fact, seems intent on trying to rebuild the fractured Republican coalition by successively transforming himself into each part of it. This week he finally persuaded someone to believe him.

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