“IT IS now clear this will be a two-person race between the conservative leader Newt Gingrich and the Massachusetts moderate.” So said the conservative leader Newt Gingrich to console himself after being trounced by Mitt Romney in the Florida primary in late January. But late January was an age ago in what America's discombobulated pundits are now calling the topsiest-turviest primary season they can remember. As the four remaining candidates brace for elections in Arizona and Michigan on February 28th, all eyes are now on the two-person race between Mr Romney, the plutocrat formerly known as the front-runner, and Rick Santorum, the social conservative and culture warrior who was never supposed to stand a chance.

Just how Mr Santorum got here is a bit of a puzzle. His campaign got off to a good start, with a narrow victory in Iowa's caucuses at the beginning of January, but he came fourth in New Hampshire and (after Jon Huntsman and Rick Perry dropped out) a poor third in South Carolina. The smell of political death hovered in the air at his thinly attended election-night party in the Citadel, a military college in Charleston. Nothing daunted, Mr Santorum soldiered on to Florida, only to finish well behind Messrs Romney and Gingrich again. And in Nevada at the beginning of this month Ron Paul pushed him down to fourth place.

And yet—hallelujah!—Mr Santorum is now being hailed as a giant-killer. On February 7th he conjured up a hat-trick of victories in Colorado, Minnesota and Missouri, and since then the force has stayed with him. National polls have him leading the Republican field. More terrifying to Mr Romney are polls that give Mr Santorum a fair chance of victory next week in Michigan. That would be a bitter reverse for Mr Romney in the first rustbelt state in the Midwest to hold a primary, the very state where he grew up and where his father was a popular governor. If Mr Santorum can win there, he might also win delegate-rich Ohio on “Super Tuesday” on March 6th, when many states will vote.

What explains Mr Santorum's surge? Dumb luck, say some. Plenty of candidates before him—Michele Bachmann, Herman Cain, Mr Perry and Mr Gingrich—have hit the Republican sweet spot too, only to be rejected once their blemishes became plainer. Looked at in this light, Mr Santorum is merely taking his turn as the final non-Romney, pushed aloft less by his own positives than by the negatives of his competitors, notably Mr Gingrich's bloated ego and Mr Romney's lack of conviction. In due time, it is argued, the laws of political gravity will pull him back down.

Mr Santorum does, after all, have negatives of his own, the main one being a divisive social agenda that threatens to make him unelectable as president even if he does win the Republican nomination. He is an agitated opponent of gay marriage at a time when Americans as a whole are becoming relaxed about such issues. He would repeal the new law that allows gays to serve openly in the armed forces and opposes abortion even in cases of rape and incest. He is on record calling contraception a “licence to do things in a sexual realm that are counter to how things are supposed to be”. And he appears literally to believe (a video shows him saying all this to students in 2008) that Satan is roaming the United States, “using those great vices of pride, vanity and sensuality” to undermine its institutions. A former aide called him “a Catholic missionary who happens to be in the Senate.”

This column has argued before that when the media look only at Mr Santorum's thoughts on family morality they end up with a caricature. He is in fact a more rounded candidate, with some impressive skills. These include not only the perseverance that kept him tramping through the slough of despond when others might have given up, but also a nimble and well-stocked mind, an approachable manner on the stump and—the big prize that eludes Mr Romney—a palpable sincerity. In Michigan and Ohio, he may also prove that he has another advantage over Mr Romney: an appeal to blue-collar workers that is hard for a member of the 1% to match. Mr Santorum takes care to give the coalmining travails of his immigrant grandfather a big place in his narrative.

Explore our <a title= interactive map and guide to the

race for the Republican candidacy" src="https://www.economist.com/sites/default/files/images/2012/04/articles/body/20111210_wop995_290.jpg" srcset="https://www.economist.com/sites/default/files/images/2012/04/articles/body/20111210_wop995_290.jpg 1x" width="290" height="163" alt="" data-slim="1" data-teg-id="hgal52ero9vpkal9dpb6b75ombo2f54n">

For all that, Mr Santorum is a very long way from becoming the nominee. Though more rounded than caricature suggests, he has a funny way of showing it. Instead of pivoting to the economy, he has wasted much of his precious turn in the limelight by returning to the culture wars. Lately he has bashed Barack Obama's “phony theology”, criticised the prenatal amniocentesis test for women (it leads too often to abortion, he says), and wondered aloud why the federal government or even the states should be in control of schools (he and his wife taught their own large brood mostly at home). Mr Romney and his super PAC are meanwhile rubbishing the former senator for loving earmarks when he was in Congress, and for lingering in Washington as a well-paid consultant after the voters of Pennsylvania kicked him out. Having used a blizzard of negative ads to beat down upstarts before, Mr Romney may succeed at doing so again next week.

And then?

The Republicans did not want their primary season to look like a coronation. That, to say the least, is no longer a danger. It is now clear only that a large share of the party's conservatives just do not like Mr Romney. This traps the party in a fratricidal exercise that could continue for months, if not all the way to the party convention in Tampa in August. Even if he loses next week in Michigan, Mr Santorum should pick up enough delegates to keep his hope alive. Mr Gingrich is unlikely to quit unless he loses in his home state of Georgia on Super Tuesday, and Mr Paul will fight on whatever happens. There is new talk of an “open” convention, where no candidate has a majority and the call goes out for a white knight, if one can be found. Mr Obama is a lucky man.

Economist.com/blogs/lexington