I wonder what Karl Rove – the man once known as Bush’s Brain – was thinking as he watched CNN’s YouTube Republican debate last Wednesday night. On the stage, we witnessed all the loose and dead ends of the postBush right. But one man seemed to stand apart.

He has a funny name and a well-honed shtick, and only recently was regarded as a novelty candidate. But he represents in many ways the natural evolution of the party that Rove crafted onto the evangelical persona of George W Bush. And he scares traditional economic conservatives rigid.

Mike Huckabee is something both old and new in American politics. The old first: he’s a former governor of Arkansas with a weight problem and a not-so-pretty ethical past in that never-very-pretty southern state. He has developed a good line about it: like Bill Clinton, he’s from Hope, Arkansas, and he’s asking the Republicans to give the place a second chance. But he has none of Clinton’s mastery of policy detail, and little of his fundraising skill. Whether his ramshackle campaign has enough money, volunteers and basic competence to stay in the race after mid-January is a matter of some doubt.

Huckabee’s strategy is also retro. If his geographical lineage is like Clinton’s, the candidacy his most resembles is Jimmy Carter’s in 1976. The country is fed up with a White House run by Dick Cheney, just as it was when Gerald Ford was president. More than 70% of people think the country is on “the wrong track”, a harbinger of a change election. One of the most attractive candidates is clearly not from Washington; and his basic appeal is one of religious sincerity and personal charm. He hopes to leverage the quirky Iowa caucuses to victory.

If Carter was the first president to exploit politically the cultural revival of American southern evangelicalism, Huckabee arrives as the movement has matured and is showing signs of splintering. Like Carter, he is steeped in Baptist culture and theology. He’s even a minister; and he proudly holds a degree in Bible studies from Ouachita Baptist University, in Ark-adelphia, Arkansas.

Unlike Carter, of course, he is a Republican.

And that is where the newness comes from. Under Ronald Reagan’s defining presidency, the Republican party backed free trade, low taxes, small government and self-reliance. Under George W Bush, the only feature of that policy mix that remained was low taxation. Bush backed steel tariffs, spent oodles on expanding government, especially in education and entitlements, and constantly touted the capacity of government to help anyone in need. “We have a responsibility,” Bush famously pronounced in 2003, “that when somebody hurts, government has got to move.”

Huckabee has the same instincts and the same objective: to remake the Republicans into a big-spending, “compassionate” party dedicated to winning over the bulk of working-class and especially rural Americans. In his races in the early 1990s, he was advised by Clinton’s guru, Dick Morris, who explained: “What we wanted to do was run a progressive campaign that would appeal to all Arkansans.”

As Arkansas governor, Huckabee raised taxes to fund education and healthcare for children. The conservative Club for Growth has calculated that he raised state spending by a whopping 63% in his tenure, and the conservative National Review claimed he added almost $1 billion to the state’s debt. But he combined this big-spending Republicanism with an absolutist position against all abortions, strong opposition to legal protections for gay couples, and an unembarrassed embrace of creationism. In his own words: “I do not necessarily buy into the traditional Darwinian theory, personally.” You can see why he seems Bush’s natural heir.

His one sop to the economic right is his proposal to abolish income tax and replace it with a national sales tax. But the rate he favours would not raise sufficient revenue to keep the budgeting neutral; and whatever benefits the country would get from scrapping the Internal Revenue Service would be overwhelmed by the intrusive bureaucracy required to ensure the poor weren’t clobbered by a tax that would hurt them the most. I know of no serious economist who thinks Huckabee’s tax proposals aren’t nuts.

Earlier this year, he was viewed as a joke. He could barely raise any money, and was regarded as a second-string figure to more established religious-right candidates such as Sam Brownback. But the debates made him. He’s actually funny, in a Reaganesque fashion, and relates to ordinary Americans in a way none of the other Republican candidates does. He appears genuine and trustworthy in a way none of the others manages. His main claim to fame is losing more than 100lb in weight – and, in a country of ubiquitous obesity, that shouldn’t be underestimated.

More to the point: in a party that has come to seem very nasty, Huckabee seems extremely nice. He’s the one leading evangelical Republican who doesn’t scare the bejesus out of Democrats and liberals. And in a party now dominated by religious fun-damentalists, he has more credibility than the Mormon Mitt Romney, and much less baggage than the war veteran John McCain. If you’re a Christian conservative, what’s not to like?

Hence the small ripple when he wowed the annual convention of the religious right earlier this year in Washington. And in Iowa, where fun-damentalists dominate the caucus, he has taken off in the past month. The latest poll shows him in the lead. Romney’s appeal to the Christian right has always been shallow and fatally compromised by his Mormonism.

Then what? Many observers think this all benefits the former New York mayor Rudy Giuliani, who is faring poorly against Romney in the early states. But that assumes Huckabee himself won’t gain momentum. Why exactly shouldn’t he? In Iowa, Huckabee is winning voters whose biggest concern is national security – which suggests that religious voters are not convinced they have to hold their noses and back the pro-choice Giuliani because of Huckabee’s lack of experience of terrorism.

My own hunch is that it’s perfectly possible that Huckabee will build up enough steam. In the south, it’s hard to see how a Rudy beats a Huckabee. And by the time Florida and California vote, in February, Huckabee may be unstoppable.

A Huckabee-Giuliani race? It could happen. If it ends up that way, you would see a classic divide between the old Republicanism and the new. Rudy’s urban, free-market authoritari-anism would be pitched against a rural, populist nice guy.

And if another evangelical southern governor were to beat a New York mayor, Rove’s transformation of the Republican party would be complete. This unlikely Baptist minister could finish off what Nixon started and Bush accelerated. And American conservatism could fully become what it has been tending towards for more than a decade: the apotheosis of the south. With a few inches off the waistline.

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