The historical analogies for the phenomenon that is Barack Obama have already stretched credibility. For a while pundits likened him to the effete loser Adlai Stevenson, the Democratic party’s 1950s version of Labour’s Hugh Gaitskell, the greatest prime minister we never had.

But Obama doesn’t seem like such an airhead after his gritty, crushing defeat of Hillary Clinton in Iowa. I long thought he’d win – but I never thought it would be by eight points, or that he’d push Clinton into third place.

So now the favourite analogy is JFK: the young, hopeful rhetorician urging a New Frontier after two terms of conservatism. But that doesn’t work either: JFK won by out-hawking Nixon in 1960, and Obama is a clear antiIraq war candidate.

Bobby Kennedy is more apposite: a mix of inner steel and an evolving moral candidacy. Just as a vote for RFK in 1968 was seen by many as a form of collective self-absolution for Vietnam, so Obama resonates among many Americans who do not recognise what their country has become these past few years.

The analogy that worries Republicans the most is a more recent one. Could Obama be a potential liberal version of Ronald Reagan? Could he do for the Democrats what Reagan did for the Republicans a quarter century ago?

It’s increasingly possible. Reagan was the cutting edge of the last realignment in American politics. With a good-natured, civil appeal to Democrats who felt abandoned by their own party under Jimmy Carter, Reagan revolutionised the reach of his own party.

He didn’t aim for a mere plurality, as Bill Clinton did. Nor did he try for a polarising 51% strategy, as George W Bush has done. He ran as a national candidate, in search of a national mandate, a proud Republican who nonetheless wanted Democrats to vote for him.

He came out of a period in which Americans had become sickened by the incompetence of their own government. Reagan shocked America’s elites by pivoting that discontent into a victory in 1980. And by his second term, he won 49 out of 50 states.

You can see the same potential in Obama. What has long been remarkable to me is how this liberal politician fails to alienate conservatives. In fact, many like him a great deal. His calm and reasoned demeanour, his crisp style, his refusal to engage in racial identity politics: these appeal to disaffected Republicans.

He is particularly attractive to those on the American right who feel betrayed by the Bush administration’s version of conservatism, just as many Democrats felt betrayed by Jimmy Carter’s liberalism.

These voters – nonevangelical, fiscally and militarily prudent, socially tolerant – do not feel at home in the angry, Southern, antiimmigrant Republican party of the past few years.

Almost a quarter of those voting in the Democratic caucus last Thursday night were Republicans or independents. In both categories, Obama beat Clinton by more than two to one.

In New Hampshire on Tuesday, independents are even more prevalent and may well represent 40% of the Democratic vote. (In both Iowa and New Hampshire, you can change your party registration on the day of the vote.)

Reagan won a national victory on the strength of “Reagan Democrats”. Obama could win with “Obama Republicans”. That’s remarkable in itself. When you realise he’s also a liberal urban black man whose middle name is Hussein, it’s gob-smacking.

Put these disaffected Republicans together with a spectrum of minorities and a black vote potentially greater than at any time in history, and you begin to see what Obama offers his own party.

The other strikingly Reaganite aspect to Obama is his appeal to the younger generation. People forget that the oldest president was extremely popular among the under30s.

Obama has an almost cult-like standing on college campuses. The youth vote is always touted every four years but never materialises on polling day.

Last Thursday, it came out in force. In Iowa, where the over65 cohort usually outnumbers the under30s by five to one, the old and the young were evenly divided. Among the under30s, Obama beat Clinton by 57% to 11%.

This generation, moreover, is a huge one: the Boomer Echo. Between Bush’s pushing them and Obama pulling them, the Democrats’ advantage could define a generation’s politics. And that’s increasingly Obama’s ambition. He has kept his ego in check, but he is clearly aiming not for a small win, but for a major mandate. He isn’t a Clinton in this respect or even a Bush. He is a Reagan, a Thatcher – of the left.

Mike Huckabee, meanwhile, is being discounted as nothing like this significant. But it is, I’d say, very foolish to underestimate him as well. In the wreckage of the postBush Republican party, Huckabee is the most talented natural politician. And he has taken Bushism to its logical conclusion.

He argues – proudly and simply – for a politics based overwhelmingly on religion. He refuses to apologise for previous statements that he wants to reclaim America for Christ or that people with Aids should be quarantined.

In Iowa, he won the born-again vote and the vote of Bush fans. He’s the kind of preacher who lets you know he likes a beer and knows his rock’n’roll. It works. One slogan seemed as powerful as it is simple: “I Like Mike”. And so many do.

And, unlike Bush, Huckabee has combined a belief in the paternalist state with a hostility to Wall Street. He is a potential builder of a future Republicanism that is as socially conservative as it is economically populist: extremely hostile to illegal immigrants, gay couples and abortion, but just as angry at big corporations, free trade and the globalised gilded elites.

In making the case against Mitt Romney – a multi-millionaire former business consultant – Huckabee argued that it was a choice between the bloke you work with and the man who sacks you.

The simmering class resentment, which is just beneath the surface, clearly motivates his supporters. When they were attacked by Washington Republicans as know-nothings, they responded by surging to the polls. They can smell the condescension. And it angers them.

It may be that Huckabee, as the conventional wisdom has it, cannot win the nomination. Underfunded, underorganised and a foreign policy embarrassment, he is unlikely to win New Hampshire against that state’s favourite old codger, John McCain, or slick neighbouring former governor of Massachusetts, Romney.

But South Carolina, brimming with evangelicals, is another matter. And talent counts. Huckabee’s underrated skills have already begun to bring in more established advisers such as former Reagan aide Ed Rollins (now Huckabee’s campaign manager) and Clinton’s scruple-free guru, Dick Morris.

Bill Clinton himself is a fan. Even if Huckabee falters this time around, he represents a viable future for the Republicans, even if it is a very different one from the past. Huckabee represents the consolidation of the Republicans as a Southern, religious, working-class party.

If he wins the nomination, he could push a lot of economic conservatives into the Democratic camp, lose badly and yet reshape his party: a reverse Goldwater, turning Republicanism into something more like religious populism than Yankee conservatism.

Am I extrapolating too much? There is, of course, a natural tendency to overestimate the import of a single caucus. But so far, the underestimaters have been the ones who have got this election wrong. Washington’s elites assumed a match between Hillary Clinton and Rudy Giuliani this year. But they didn’t see the turmoil remaking America, and the deep hunger for a new direction. As unrest grows in Pakistan, as the American economy looks headed for a nasty downturn, I see no reason to think that the forces behind Obama and Huckabee will abate soon.

Yes, history happens. And Americans, exhausted from fear and war and economic insecurity, have just informed us that they can shape it again. I wouldn’t bet against them.