The most surreal moment in my somewhat limited career as a television commentator came when I was a studio "expert" analysing the results of the 1992 British general election live, as they came in. I was on the air when PBS switched to the announcement of John Major's result in Huntingdon (the US producer presumably failing to understand the British parliamentary system and therefore believing Major's local result to be of national significance). To my alarm, I could see the anchorman becoming excited: in the line-up of candidates opposing Major he had singled one out. Then he looked me solemnly in the eye and asked: "Andrew, exactly who is Lord David Sutch and what is the Monster Raving Loony Party?"

Well, Bob, I stammered away - this was after something like four hours on the air - it's like this. No, Sutch isn't really a Lord and he doesn't have a party to speak of. It's all really just a harmless British tradition: this man, I said, is a former pop singer who stands in every election, usually in a constituency where he gets the most attention. No, Bob, he stands no chance of winning. Policies? Well, no, he doesn't really have any. His top hat? He wears that for the result of every election. With every succeeding word, I could feel my credibility as an authoritative commentator on British affairs crumbling away. In the stiflingly politically correct ambiance of PBS, who could possibly explain the late, lamented Sutch and simultaneously keep a straight face?

The point I could not get across was that Sutch was a political joke to all concerned (including himself) and that nobody was meant to take him seriously. Americans found this peculiarly bewildering. Except for Ronald Reagan - and he was then still being taken extremely seriously - no candidate in US politics had ever made the crossover from fantasy to reality, after all. "A joke, Andrew? OK. Now it looks as though Prime Minister Major is saying something [cameras switch to Major]. 'On behalf of all my constituents, I'd like to thank the returning officer . . . 'Returning officer, Andrew? What British government office-holder is that?"

Fast-forward to 1999, though, and a transatlantic twist is in full swing. This is turning out to be the year of the vanity candidate here - with people no less absurd than Sutch appearing everywhere, except that his American equivalents are being taken seriously. Would anyone have believed that a 48-year-old, moderately successful, 6ft 4ins, 18-stone former bald wrestler - famed for wearing a boa feather in the ring - could first be elected governor of Minnesota and then be regarded as a serious presidential contender for 2004? That the US media is now seriously awaiting word from a 62-year-old intellectually challenged actor named Warren Beatty about whether he will stand for the presidency next year? That a stupendously unattractive property developer called Donald Trump, 53 - who is paranoid about shaking hands with germ-ridden strangers - is spoken of in breathless, expectant tones?

There is a serious and potentially very important reason, however, why all these people are suddenly being taken at least somewhat seriously. In 1992, Ross Perot - a Texan billionaire with huge ears - seemed an acceptable alternative to either George Bush Sr or Bill Clinton to no fewer than 19 per cent of American voters as the "Reform" Party candidate; in so doing, he won more votes than any third-party candidate since Theodore Roosevelt in 1912. Only George Wallace in 1968 (with 13.5 per cent) and John Anderson in 1980 (with 7 per cent) came close. Perot slipped in the 1996 election when he won only 8.5 per cent, but these achievements have been enough to give the Reform Party a serious platform - and $12.5 million in federal funds - to fight next year's presidential election.

This ready-made platform is enabling anybody famous or rich - ie, any American celebrity - to put themselves forward as serious candidates. The former wrestler, Jesse "The Bull" Ventura, won himself the governorship of Minnesota by standing as the Reform Party candidate - he is now busily planning to illuminate his state mansion with 20,000 orange lights for Halloween - and is positioning himself as a presidential candidate for 2004.

In an interview in next month's Playboy, Ventura neatly demonstrates the growing convergence here between showbiz and politics: he quotes a profound adage uttered by "my friend" Jack Nicholson, when Nicholson apparently pronounced the words: "You can't handle the truth." Like Reagan, Ventura is clearly unable to distinguish between lines said from a film-script and everyday reality. Nicholson uttered those words as a fictional character in a fictional movie called A Few Good Men. Beatty, presumably, could utter scripted words like a pro, too. And Arnie Schwarzenegger is a real serious candidate as well.

We joke at our peril about any of these American Sutches, much as commentators once jeered at a B-movie actor called Ronald Reagan. There are plenty of other reasons, too, to take the Reform Party seriously - if only because of the way it has affected the policies and actions of both Democrats and Republicans.

Now the most likely Reform candidate looks to be the populist rabble-rouser Pat Buchanan, who says both Britain and the US should have kept out of the second world war. His imminent defection from the Republicans to be the Reform Party's presidential candidate next year will be a very serious blow indeed to George Bush Jr, as Buchanan is bound to take a lot of mainstream Republican support with him. Yes, Sutch would have loved it: the raving loonies are finally a serious force, not in the UK but across the Atlantic.