The arrest this week in Denver of some gun-toting, meth-fuelled white supremacists supposedly bent on assassinating Barack Obama neatly fits a narrative that has considerable appeal for many observers of the 2008 campaign.

There’s a common view among Democrats and their supporters in the media that the reason Mr Obama is struggling to gain a lead in the polls in what should be a banner year for Democrats is simple: racism.

Four fifths of Americans say that the US is on the wrong track; Republicans in Congress are heading for a setback of historic proportions; the desire for a change in political direction is palpable.

But Mr Obama is running neck and neck with John McCain. And it’s clear from detailed polling data that Mr Obama’s big problem is among working–class white voters (rednecks, in the derisive popular description favoured by their civilised, educated betters). QED: a black man can’t get elected President.

There are lots of things wrong with this idea other than the general tone of scented– handkerchief–in-front-of-the-nose patronising metropolitan elitism.

No one doubts that there are Americans for whom a candidate’s race is enough to disqualify him or her for the presidency. But there is no reason to think that their influence in this election is decisive.

For one thing, the Democratic candidate’s race is clearly an advantage in some respects. Two large demographic groups whose turnout in general elections is notoriously low — blacks and young people — seem certain to come out and vote for him in November in larger numbers than they have ever voted before. That alone might be enough to counterbalance the racist vote.

In any case, the racism argument forgets that majorities of white, working-class voters have not voted for previous Democratic candidates for decades. Since Ronald Reagan swung blue-collar voters behind him in 1980, no Democrat has won a majority of the white, working-class vote.

In fact, Mr Obama is faring exactly the same among white voters without a college education as John Kerry did in 2004 — with 38 per cent of that vote, according to the latest poll average.

Of course, he should — given the changes in the relative strength of the two parties in the past four years — be doing somewhat better. So why isn’t he?

Part of the answer is provided in a fascinating new study of voters in one of the most closely scrutinised places in the US. Stanley Greenberg is the Democratic pollster who broke new ground in the study of voting behaviour with an analysis of the so-called Reagan Democrats in Macomb County, Michigan, in the 1980s. White, blue-collar voters in this Detroit suburb voted 2-1 for Reagan in 1984.

In his landmark analysis, based on focus groups with former Democratic voters, Greenberg found that race was indeed a significant factor among those white, working-class voters. They interpreted Democratic calls for economic fairness in the 1980s as a veiled plan to channel government spending to African-Americans and they strongly disapproved. Greenberg was influential later in crafting Bill Clinton’s “New Democratic” message of personal responsibility alongside economic fairness, which won over the Reagan Democrats.

Last month Greenberg returned to Macomb County to gauge opinions about Mr Obama. He found high levels of dissatisfaction with the state of the country but also a surprising degree of doubt about the Democratic nominee. He was winning the support of only half those who said they thought the country was on the wrong track.

Race clearly played a part with some voters. But, according to Greenberg, if anything, colour seems to be less of an issue than it was back in the 1980s.

“Macomb voters do not seem to be voting predominantly on race,” the study concluded. Instead, Mr Obama faces two problems. The first is his failure to connect with voters on their economic anxieties. This seems to be a direct result of his decision to campaign on the loftier goals of change and renewal, and not on unemployment and falling real incomes.

The other concern was a widespread doubt about Mr Obama’s suitability to be commander-in-chief. Macomb voters are much more focused today on national security than they were 25 years ago, and they worry about Mr Obama’s inexperience. They also express doubts about his patriotism, often citing the incendiary antiAmerican remarks of his mentor in Chicago, the Rev Jeremiah Wright.

In short, Mr Obama’s biggest problems lie in his own perceived political weaknesses, not in the colour of his skin.

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