Why isn’t Obama farther ahead in the polling? The objective factors that favor the Democrats this year are overwhelming: the worst economy since the Great Depression, the most unpopular incumbent president in the history of polling, and a money advantage in the campaign that is unprecedented for a Democrat. The polls all show that Obama will win – but the authoritative polling statistics website, FiveThirtyEight.com, predicts that Obama will end up with 52 per cent of the vote.

If Obama does get 52 per cent of the white vote today, that will be more than any Democrat in the last 40 years – more than Bill Clinton, who got 49.2 per cent in 1996 (when Ross Perot got 8.4 per cent) and more than Jimmy Carter, who got 50.1 per cent in 1976. But it’s nowhere near LBJ’s 60.1 per cent in 1964, or Ronald Reagan’s 58.8 percent in 1984.

One reason why Obama isn’t farther ahead may be race. The evidence here is of course problematic. When the New York Times-CBS poll in August asked white people whether they would vote for a black presidential candidate, only five per cent said "no"–impressive evidence that America has at last overcome its racist past.

But the pollsters asked a number of other questions to uncover racist attitudes: do you think an Obama administration would favor blacks over whites? 16 per cent of whites said "yes." Do you think America is ready for a black president? 24 per cent of whites said "no." And the question pollsters consider the most significant: do you agree or disagree with the statement, "Most of the people I know would not vote for a black presidential candidate"? 19 per cent of whites agreed.

All this suggests the number of white likely voters who will vote against Obama today because he is black is somewhere between 16 and 24 per cent. That’s something like 25 or 30 million racist white votes against Obama – more than the total number of black voters.

On the other hand: Obama has more support from white voters than any Democratic candidate in the last 30 years. According to another New York Times-CBS poll, 44 per cent of whites support Obama. If he ends up tonight with that 44 per cent, that will be more than supported Kerry, who got 41 per cent; more than Gore, who got 43 per cent; and more than Clinton in 1996, who also got 43 percent. Only Jimmy Carter got more: 47 per cent, and of course he was a southern white man.

The reason why more whites support Obama than any Democrat in the last 30 years is not hard to find: "it’s the economy, stupid" — that, and Obama’s steady and calm focus on economic issues.

But if it were up to whites, McCain would almost certainly be our next president. Obama can win only with the vote of nonwhites – a fact well known to Republicans, who have spent years working to reduce the number of black voters through new voter ID laws, purges of the voter rolls, felon disfranchisement, insufficient voting equipment in black precincts, and other well-known factors. The Obama campaign surely knows all about this, and is prepared to fight fiercely to protect the vote.

One other crucial factor: America is significantly less white today than it was a decade or two ago. As John Harwood of the New York Times pointed out on Monday, when Reagan won reelection in 1984, the electorate was 86 per cent white; by 2004, the white percentage had dropped to 77. That’s one reason why an interracial coalition is likely to elect America’s first black president today.