I'll put my money on John Kerry to win

It will be because of higher turnout. And I'll go further and say that that he'll win decisively

Tomorrow US voters will turn out in greater number than usual. That is the only forecast about the presidential election that can be made with confidence - though I shall venture further. I got my first sense of how hard fought this Bush vs Kerry tussle would be last August when I was on holiday in the United States. Three times I was stopped in the street by party activists seeking to enlist my support. Now, months later, the fight has reached its final stage, which is known as "the ground war", the effort to get every supporter to the polls.

There are recent precedents for increased turnout. It was sharply up in the Spanish election which booted out the pro-Bush government. A few months later even the routine French regional elections attracted higher participation and produced an equally stunning result - the Socialist party captured almost every regional administration. France had quickly become impatient with its rulers.

Neither result was forecast by the opinion polls conducted in the preceding weeks.

It is because of higher turnout that I believe Kerry will win. And I will go further and say that he will do so decisively. There will be legal challenges in individual states but not on a sufficient scale to put the outcome in doubt. Isn't there a lot of wishful thinking in my forecast? Undoubtedly, but let's see.

One reason for expecting a higher turnout is that part of the electorate will want to repudiate the slick political marketing to which it has been subjected. We won't be spun; we'll vote! While Republicans and Democrats have tried equally hard to bamboozle people, voters can see that in this respect the incumbent always has an advantage through control of the machinery of government. Electors who feel manipulated are thus more likely to vote and to cast their ballots for John Kerry than George Bush.

The electorate is always more active, too, when a big issue presents itself. For example, the referendum on the Good Friday peace process in Ulster saw 90 per cent of the province's electorate go to the polls. The perceived terrorist threat to the US is of this order of importance. ( I say "perceived" because, contrary to what one might imagine, there have been very few terrorist outrages in the United States or Britain since 9/11). However when turnout rises, then the likelihood is that what is propelling more people to the polls is dissatisfaction with the status quo. The Spanish election taught that lesson very clearly. That's the argument for a Kerry victory.

In this light, the significance of Osama bin Laden's late intervention in the election is that it reinforces the notion that the outstanding issue is security. If anything, therefore, his broadcast will send more people to the polling booths. It won't, however, change any voting intentions.

A team of reporters sent into five key states by The New York Times couldn't find a single person who said the Bin Laden tape would change his or her mind. "We're dug in," said one. "People I know are so polarised, it doesn't make any difference," said another. A third remarked: "I don't think people are really responding any more, we're shellshocked." Many people said that while Bin Laden remained a potent symbol, the issues raised by the election were bigger than one man, and that Bin Laden's words, at this point, would not make any difference to how people voted.

Yes, but hasn't Mr Bush been able to enlist a very large constituency in the United States, committed Christians with conservative social views, Roman Catholics as well as Southern Baptists? Their battle cry is that this presidential race, more than any before, is a contest pitting faithful of all kinds against unbelievers. The news service of the Christian Broadcasting Network, citing polls, recently summed it up another way: "Those who pray a lot tend to vote Republican. Those who don't tend to vote Democrat."

Indeed there is truth in this. A Pew Forum poll last week found that 53 per cent of regular churchgoers supported Mr Bush while 38 per cent supported Mr Kerry. Yet this is not a new phenomenon but, rather, a developing one. And it arouses the opposition of all those whom this conservative Christian movement has in its line of fire - women who want to make their own decisions about abortion, people who have been divorced, mothers trying to bring up families on their own, people with fatal illnesses whom stem cell research could help, the gay community. All of these are more likely to vote for Mr Kerry.

What an election. So hard to predict. Yet I place my bet on John Kerry. And if I am right, what would this mean for our Prime Minister, Tony Blair. Some say Mr Blair would look horribly isolated in relation to the Iraq war; yet others argue that he would regain his freedom of action. I see another consequence. With Mr Bush leaving the White House, many people who have been frightened of revealing what they know about the preparations for the war against Iraq and about its chaotic aftermath would feel free to speak out. And some of what they reveal would tell us more about the precise role of the British Prime Minister in the Iraq calamity. Mr Blair might not enjoy that.