A wing and a prayer: with 24 hours to go, candidates make their final pitch

The race for the White House was a dead heat last night with little evidence that either candidate is gathering any last-minute burst of momentum or any clear suggestion that the release of a new Osama bin Laden videotape has significantly altered the electoral landscape.

The race for the White House was a dead heat last night with little evidence that either candidate is gathering any last-minute burst of momentum or any clear suggestion that the release of a new Osama bin Laden videotape has significantly altered the electoral landscape.

Still neck and neck, both candidates appeared at rallies in two of the most vital states in the race - Florida and Ohio - with Senator John Kerry also making a quick visit to New Hampshire. Each man used the last hours of campaigning to batter and mock the other as ill-suited to be the country's leader.

While the Bin Laden message appeared at first to be the "October Surprise" that every campaign fears in the last days of a presidential campaign, it seemed that the level of influence on voters may be minimal. But, with this race so tight, every small breeze could be enough to change the outcome.

Pollsters remained at a loss, their difficulties compounded by the likelihood of a very high turnout and uncertainty over which candidate stands to gain more from it.

There was cautious confidence at the start of the weekend inside the Bush camp that the Bin Laden tape would give them some advantage after several days when bad news - ranging from missing explosives in Iraq to an FBI investigation into contracts awarded to Halliburton, formerly headed by Dick Cheney - had worked against them. "We're going to carry Florida and win a victory," a visibly charged George Bush told supporters at the Miami rally after scorning Mr Kerry for inconsistency. "He has entered the flip-flop Hall of Fame," he quipped to huge applause.

That optimism was bolstered by a Newsweek poll taken between Wednesday and Friday - before news of the Bin Laden tape had broken - that showed Mr Bush leading Mr Kerry by 50 to 44 per cent with a four-point margin of error.

However, most other polls still showed both men in a statistical dead heat.

The daily tracking poll from the Zogby Organisation yesterday showed Bush and Kerry stuck in a dead heat, each with 48 per cent support.

Most polls also showed that a majority of Americans fully expect that the battle for the White House will not be resolved tomorrow but will end up in the courts, as did the presidential contest four years ago.

While the poll numbers try to describe popular sentiment, they do not help fathom how each man has fared in the more relevant battle: gathering together the states they need to accumulate the 270 majority to take the electoral college which finally determines who gets the keys to the White House. Most energies are being focused on five states - Ohio, Pennsylvania, Wisconsin, Iowa and Florida, which, with 27 college votes (a tenth of the necessary majority) represents the biggest prize of all.

While Mr Bush made a lunchtime appearance in Miami yesterday, Mr Kerry was on his way to Tampa, which sits in an area of Florida considered to be on a knife-edge between the two men. After their Florida engagements both candidates were due to travel to the Midwest.

As with several other battle-ground states, turnout is the most important factor in Florida, where both men also appear to be neck and neck.

"It's going right down to the wire again in Florida. In this kind of race, with so few voters left undecided, it comes down to three things - turnout, turnout and turnout," said Clay Richards, assistant director of the Quinnipiac University Polling Institute in New York.

Divining Florida's intentions is all the harder because as many as 20 per cent of voters in the state are expected to have taken advantage of expanded opportunities to cast their ballots before tomorrow.

This could be good news for Mr Kerry in Florida, although even that is not certain. But historically, large volumes of early voters have tended to help Democrats. Indeed, early indications suggest that early voters have been running heavily his favour in Florida. But Republicans say they are not afraid of the trend, pointing out that larger numbers of absentee ballots are expected to be cast than usual, many coming from military personnel abroad.

Karl Rove, the President's top political adviser, dismissed any suggestion that early voting would count against the Republicans. "In early voting, the Democrats are doing better than we are," he said. "In the absentee ballots, we are doing better than the Democrats. When you add the two together, we are doing better than the Democrats."

Scenarios abound of possible electoral deadlock after the polls close on Tuesday. Each camp is ready to bombard the courts with lawsuits where any issues of fraud or disenfranchisement are detected.

Some pollsters warn of the possibility that the mathematics of the swing states provide the possibility that the candidates will end up tied.