A couple of minor, isolated polls in the past ten days have hinted that Mr Obama would top 50 but yesterday, with three weeks until the election, an ABC News/Washington Post poll gave the Democrat a ten-point lead of 53 points to John McCain's 43. Gallup gave him a more modest 52 to 43 lead and a Rasmussen poll put Mr Obama's lead at 50 to 45.

Mr Obama yesterday sought to consolidate his lead by unveiling a rescue plan to tackle the economic crisis. At a rally in Toledo, Ohio, he said: "This crisis has taught us that we can't have a strong economy with a dysfunctional financial system.

"If we are honest with ourselves, everyone was living beyond their means."

The plan includes a three-month moratorium on mortgage foreclosures, a major worry for millions of homeowners, together with previously outlined plans for protectionist tax breaks to stop the export of jobs.

Mr McCain promised his own set of new economic initiatives in a relaunched campaign, promising a plan to use government cash to bail-out failing mortgages.

He told supporters at Virginia Beach, Virginia: "Let me give you the state of the race today. We have 22 days to go.

"We're six points down. The national media has written us off."

Details of Mr McCain's plan are expected later this week, but one confidant, Senator Lindsey Graham, promised a big hit: "It will be a very comprehensive approach to jump-start the economy."

Mr McCain yesterday sought to turn his opponent's advantage against him, portraying Mr Obama as complacent.

He said: "Mr Obama is already measuring the drapes for the White House. My friends, we've got them just where we want them."

Not all Republicans would necessarily agree; Mr McCain is losing ground not just nationally but in the swing states where the election is likely to be decided.

Electoral mathematics means Mr Obama needs to win just one of the five biggest swing states to get to the White House.

Currently, he has steady leads in three of them: Florida, Missouri and Virginia, and is neck-and-neck with Mr McCain in Ohio and North Carolina.

Even if Mr McCain can hold all five, Mr Obama still wins if he can hold the 5-11 point leads he now enjoys in the western states of Colorado and Nevada.

To win back lost ground, Mr McCain must correct a growing perception that he blows with the wind. When the financial crisis first broke last month, the Republican cancelled his appearance at the first presidential debate and flew to Washington to try to broker the first version of the Wall Street bail-out plan.

He was forced into an awkward reverse and attended the debate after all.

Next, he tried to divert voter attention from a meltdown blamed on Republicans by turning his fire on Mr Obama's character. But the contention by his running mate, Sarah Palin that Mr Obama consorts with terrorists backfired last week when racist and xenophobic chants broke out at Republican rallies.

So once again, Mr McCain has veered back to the economy.

Philip Klein, a columnist on the American Spectator, said: "He's been all over the place in the past few weeks. He needs to re-establish himself as a mature, steady hand."

Of the two campaigns, Mr Obama's is the most energetic: returns show that in the past five weeks, Mr Obama, his wife Michelle and running mate Joe Biden have made 95 appearances, nearly double the 55 clocked up by Mr McCain, his wife Cindy and Mrs Palin.

Experts wonder how Bradley Effect will affect vote

IN AMERICA, they call it the Bradley Effect: the name given to a voter quirk that right now is the biggest single uncertainty in the presidential race.

Tom Bradley was a popular black Democratic mayor of Los Angeles who ran for California governor in 1982. Throughout the campaign, Mr Bradley held a comfortable poll lead over his white rival, but ended up losing the election.

Exit polls later showed that white voters had shied away from Mr Bradley by six points: apparently, they had told pollsters they liked him, but inside the voting booth chose not to support a black man.

Now pollsters are wondering if history could be repeating itself. Washington University researchers say that, based on analysis of polling and voting in the primary elections, the Bradley Effect could shave three or four points off Mr Obama's lead. But the Bradley Effect can cut both ways: in 12 out of the 32 primaries surveyed, Mr Obama actually out-performed his polled predictions, leading to speculation that whites who had been prejudiced may have left discrimination at the polling station door.

Nobody knows how widespread racist sentiment in America is, because few polls ask the question. How can they expect a straight answer in a country where stating a racial prejudice can be a crime?