Sarah Churchwell: His skin colour won't stop Obama. The colour of his politics might...

Ever since Barack Obama clinched the Democratic nomination, one question has preoccupied the European media: is America ready for a black president? This seems to me a silly question but clearly it needs answering. Logically, there are four possible responses: America is ready, and Obama will be elected; America is ready, and Obama will not be elected; America is not ready, and Obama will be elected; America is not ready, and Obama will not be elected.

But only two of these possibilities have been acknowledged, as simple binary oppositions with an implied causation. If he is elected, America is ready; if he is not elected, America is not ready. But what happens if he is elected and we're not ready? Will he wait for us while we finish getting ready? What if we were ready, but he wasn't elected?

Surely this one man is not the sole gauge on our country's moral barometer? Even the benighted Bush appointed the first – and second – African Americans as Secretaries of State. If Obama is elected, it will presumably demonstrate that we were, in fact, ready. But that's the only conclusive outcome; if Obama is not elected it will not prove that America wasn't "ready" for a black president, although that is the conclusion that the rest of the world, and plenty of Americans, will draw. It will only prove that they didn't vote for this one.

The implicit impatience, and doubt, in the question – aren't you ready yet? – suggests that America is lagging behind, a developmentally challenged nation of ignorant bigots uniquely trapped in our own solipsistic history. No sane person doubts the toxic residue of plantation slavery and Jim Crow apartheid, a poisonous history with no obvious remedy. Perhaps I'm ignorant – I am, after all, American – but I'm struggling to recall the first viable black candidate in the UK for prime minister.

The tenor of the response to Obama's nomination suggests that it is belated, but I'm pretty sure America has just become the first Anglo-European nation in history to nominate a black man in a national leadership contest. Far from taking this as evidence of my compatriots' progressiveness, however, commentators have rushed to reinforce "America's" presumptive racism.

Take for example a recent Guardian Unlimited piece, which argued that progressive Democrats are unrepresentative of the nation and thus led "us to believe that America is much more racially tolerant than it really is ... With Obama now standing as a presidential candidate against John McCain ... the true picture regarding American attitudes toward race is about to emerge." Good to see you're keeping an open mind. Why do McCain's supporters offer a "truer" picture of America than Obama's? Because they conform to European stereotypes about book-burning, Bible-thumping, gun-toting yahoos?

"America" is not a person (neither is its offspring, "Middle America"). It is not an ignorant redneck in a baseball cap and a pickup truck. There is no such thing as "American attitudes toward race", because they aren't monolithic. There are only Americans' attitudes toward race, and good luck getting a "true" picture of those. There are only 304,267,748 of them, so that shouldn't take long.

To be fair, Americans are also feverishly trying to predict America's attitudes to race. In order to do so, pollsters went to white Democrats as they emerged from primary ballots and asked them to identify whether race was: a) the most important factor in their voting choice, b) one of several factors, or c) not a factor.

The results, according to Newsweek and other reports, were worryingly "racist", because on the "Racial Resentment Index" (their phrase, not mine) a statistically significant sample of Clinton's supporters put race as a very important factor in their support for her campaign.

And who are these "high Racial Resentment Index voters"? They are primarily "low-information", "under-educated", "low-income", "downscale", older and Southern. In other words, the answers rapidly stop having anything to do with race, and start having everything to do with class, as determined by socio-economic status, region and education.

But the pollsters asked some leading questions and – surprise! – found what they were looking for: racial resentment. These people, we are told, represent the "real America", the truth about America's racial attitudes. And yet class boundaries are what are being so consistently, yet tentatively demarcated. I've written about the historical origins of this elision before, but it is a powerful equation in the American imaginary: poor, ignorant and racist. Or, to quote Gene Wilder's immortal line from Blazing Saddles: "You've got to remember that these are just simple farmers. These are people of the land. The common clay of the new West. You know – morons."

Unsurprisingly, the common folk of the American heartland don't like being called morons. So they sneer right back at those not prefixed by non-, un-, low- and down-, otherwise known as the "liberal elites": privileged, over-educated, high-income, upscale. America is just as polarised along class lines as along racial ones. So when Obama, an Ivy-League, latté-quaffing, weight-watching Democrat went to San Francisco, capital of Liberal America, and dismissed working-class America's values (guns and God) as residual economic bitterness, he confirmed their suspicions about "liberal elites", and mightily pissed them off. Doubtless some of the people in this group are racist: there are plenty of white supremacists hiding behind the Bushes. But the point is that you can't clearly disentangle class hostilities in America from racial ones. Far more conservatives won't vote for Obama because they see in him a tax-and-spend liberal who is soft on national security, just as they saw in failed Democratic candidates for the White house John Kerry, Al Gore, Michael Dukakis, Walter Mondale and George McGovern. George W Bush won two elections by pretending to be a ranch-hand from Texas instead of a Connecticut blue-blood who went to Yale.

It is far easier to play the class card in America than the race card – as we saw with the Clintons' primary blunders. McCain can't use race explicitly in his campaign – and to be fair, I have no reason to suppose he wants to (except that I would put nothing past a man who, it has been alleged and not denied, has called his own wife a cunt). More to the point, he doesn't need to handle such a double-edged sword. It is impossible to say how much latent racism will play into his hands; he needn't try, and we shouldn't. He can attack Obama on experience, national security, his links to unpatriotic rabble-rousers, and so-called lunchbox issues, while quietly encouraging the rumours that Obama is a godless Muslim. In other words, any racist who needs a different excuse to vote against Obama will be spoilt for choice.

And if Obama does win, America still won't be out of the racist backwoods for some, because many observers will argue that Obama isn't "really" black. He's the kind of black man that latently racist whites accept: non-threatening, light-skinned, good-looking, well-educated. But saying that Obama isn't really black is the same as saying that for an American I'm comparatively enlightened or for a blonde I'm reasonably intelligent.

If you believe that America is a racist nation, then electing a black man isn't going to change your mind; you'll find a way to make him the exception. There will unfortunately doubtless be white people who vote against Obama because he is black, but there will also be white people who vote for Obama because he is black.

Plenty of white Americans are exhilarated at the prospect of our nation's higher ideals finally triumphing over its baser instincts. As comedian Chris Rock said: "Is America ready for a black president or a woman president? We fucking ought to be, we just had a retarded one."

People vote to protect what they consider their best interests and their core values; they vote to protect their power. Some people define their sense of power, and their value systems, as racially determined. (These people are not, of course, only white.) But by no means all Americans, not even all the Americans in the red states, think that way, and it is staggeringly reductive to claim that they do.

It is also counter-productive: antagonising independent voters by implying that anyone who votes against Obama is a racist is not going to be a very successful strategy. I was one of the white women who had serious doubts about Clinton's probity, and I am one of the liberal progressives who has serious doubts about Obama's substance. And I'm as representative as any other American. I just have far bigger doubts about McCain: because of what he says about (and to) women, and foreign policy, and economics; because he's pledged to continue Bush's unconstitutional wire-tapping; because his own experience of torture didn't teach him it is wrong, which not only makes him seem immoral, it also suggests he isn't very bright.

If Obama wins, I will celebrate, but only in part for the historically symbolic racial triumph he represents. For if we can only see in Obama the first black candidate for president, then we are the ones judging him by the colour of his skin, and not by the content of his character.

Sarah Churchwell is a senior lecturer in American literature and culture at the University of East Anglia