As I watched the news bulletins, 5,000 miles away, I could not keep down a feeling of euphoria. America is back. Whichever way this contest now goes, the US will once again become a force for progress in a world that for too long has been able to demonise America - with the help of the crude stereotypes so readily supplied by the White House.

All three of the serious contenders break the bone-headed stereotype. Only Barack Obama and John McCain, extraordinarily good at bridging the partisan divide, could have left Hillary Clinton, potentially America's first woman president, looking like the dull incumbent.

Although he is the white man, Mr McCain's fortunes have already changed the political landscape. Despite the late surge for pastor Huckabee, Super Tuesday was a death-rattle for social conservatism. A Republican Party whose members still give George Bush a 70 per cent approval rating is out of step with the rest of the nation, and starting to worry about it. So Republicans are swallowing their bile about Mr McCain's stance on climate change and immigration and are talking him up as a war hero. Incredibly, the Republicans have a chance to hold the White House for another term.

The deadlocked Democrats are no less exciting. Even a few days ago, the consensus was that the Clinton machine was unbeatable, having banked so many IOUs from unions and Hispanic and women's groups. Worries about the economy have favoured Mrs Clinton and distracted from her Iraq record. But Super Tuesday was not conclusive. The New York Times, having endorsed Senator Clinton only two weeks ago, sounds increasingly lovelorn for her rival. Money is flowing to Mr Obama like a flash-flood.

The numbers say that this is still Mrs Clinton's election to lose. But the mood feels different. As a woman I find the Hillary conundrum difficult. I admire her doggedness and her balls. But I am repelled by her sense of entitlement. I resent her two-for-one strategy: “Get me and you get Bill too.” Is she not running in her own right? I would be proud to see a woman president. But the wrong woman could renew some bad old prejudices. The very symbolism of selecting a female president or a black president demands that the office-holder be above scandal. Hillary Clinton is not.

The Clinton and Obama speeches on Tuesday night were worlds apart: one smug and plodding, one soaring and at ease. “Nothing changes,” said Mr Obama, “because lobbyists write another cheque or politicians start worrying about how to win the next election.” Ouch. In Bill's time, the ruthlessness of the Clinton machine was softened by his genuine interest in people. But Mrs Clinton doesn't seem to like people so much. She says that she toughed it out against Republican attacks over many years, unlike the callow Obama. But “better the devil you know” seems a gauche sales pitch when the country seems to yearn for a new politics, and Mr Obama's offer of a jump into the dark is lit by braziers of hope.

I worry that I am guilty of female misogyny here. I know that women judge other women harshly in public life. Society is suspicious of women who are openly ambitious. It is quick to criticise their appearance, their tone. If that is misogyny, many of my American girlfriends are guilty. But I refuse to accept that the anti-Hillary movement is simply anti-woman. Yes, we do tend to hold women to higher standards than men in politics. But the same is probably true of minorities. And there is something about Mrs Clinton that seems narrow and polarising.

For all the hype about healing in this race, there is a danger that it could leave America less, not more, united. Whoever succeeds for the Democrats will have a struggle to win over the other's supporters, and then voters, countrywide. There is a risk, with Mr Obama, that a cult of personality is developing. But he seeks to transcend the politics of race, while the Clintons have emphasised her gender and sought to bring race into the equation.

On one reading, the Super Tuesday polls make Mrs Clinton the unifying candidate. Asian and Latino voters and white women were more likely to vote for her, while black voters went overwhelmingly for Mr Obama. But Mrs Clinton does not have a monopoly on women. Her rival won majorities of women in four states and a majority of white voters in three mainly white states - Illinois, New Mexico and Utah - by big margins. That gives him succour on a key question for his candidacy: whether America is ready to put a black man into the White House.

The most important statistic is this: while Mrs Clinton had a five-point edge with Democrats on Tuesday, Mr Obama had a 21-point lead among independents. That makes Senator Obama by far the most likely to heal partisan divisions, and to beat John McCain for the presidency.

The coming election is not about policy, where the differences are minimal between the candidates. It is about identity: what face - literally - America presents to the world. The next president needs to bring this country out of its unusual gloom. To prove that America can be intelligent and thoughtful and compassionate. In short, to make America truly powerful again. For it has never been clearer that firepower and cash alone cannot combat threats such as Islamist extremism.

Anti-Americanism was not born with George Bush Jr: it will always exist. But Mr Obama would do most to confound the stereotype. Meanwhile, this race is making Americans I know feel good about being American again. And the rest of us are feeling good about America. Long may that last.

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