Primary Colors by Anonymous Chatto, pounds 15.99 A roman-a-clef is the talk of Washington's dinner party circuit. It has Rupert Cornwell's vote
Take one of the most rollicking US election campaigns of the century. Next, write a book about it, expletives, dirty tricks, furtive copulations and all, as a roman-a-clef account of a young Southern Governor's quest for the Presidency. Time publication to coincide with the subsequent campaign, in which our hero (real-life this time) is seeking a second White House term. Finally, keep secret the identity of the author. Whether the idea came from the Random House publicity department, or Anonymous himself, is immaterial. It has has been a stroke of marketing genius.

A month after the book appeared in the US, the mystery of who wrote Primary Colors - or rather the story of how Bill Clinton won the Democratic nomination in 1992 - is still the favoured topic of the Washington and New York dinner party circuit, generating sales of over half a million. Everybody is on the case; even Bob Woodward, keeper of the only other comparable secret of recent years, the identity of Deep Throat, the source who helped crack Watergate. As this edition testifies, the fame of Anonymous is spreading beyond America. And rightly so.

Let it be said at once: fact or fiction, Primary Colors is a wonderful read. Opinions are divided on the author's provenance, although the eerie accuracy with which certain episodes and incidents are portrayed suggests he is either a journalist who covered the 1992 election (but did a journalist ever shun a byline?) or a high-level Clinton campaign worker (in which case the crime is not modesty but treachery). But he can write.

Apart from the central characters of Governor Jack Stanton / Bill Clinton and his wife Susan / Hillary, his erstwhile paramour Cashmere McLeod / Gennifer Flowers and a governor called Orlando Ozio (Mario Cuomo), the real-life models of most of the cast will only be deduced by the most assiduous followers of US politics. But it hardly matters. For the record the narrator, a strategist called Henry Burton, has uncanny similarities to George Stephanopoulos, one of Clinton's closest advisers. Henry's girlfriend, Daisy, is unmistakeably the campaign's media adviser Mandy Grunwald (whose novelist sister Lisa is a prime suspect for Anonymous).

The manic campaign manager Richard Jemmons is a dead-ringer for the manic James Carville who actually did manage the famous "War Room" in Little Rock (Mammoth Falls in the book) with Stephanopoulos. Best of all though is Olivia Holden, a surreal version of Betsey Wright, the Clinton aide in charge of dousing the Flowers and other "bimbo eruptions." Holden is spellbinding, herself a Mount Etna of demonic resourcefulness and profanity, who terrifies all who come near her.

Yes, it's unbelievable - except if you lived through Election 1992 and saw the Clintonites in action. An American Presidential campaign is an exercise in controlled lunacy unmatched on the planet. And never was a campaign more lunatic than Clinton's. Primary Colors conveys the nether- world to perfection; the numbing, endless blur of travel, days and nights without sleep, 3am strategy sessions in New Hampshire motel rooms amid the remains of yesterday's takeaway pizzas, the ever-presence of the reporters, or "scorps", and sudden all-enveloping crises.

Above all there is Jack Stanton, his eye as roving as his mind, every appetite gargantuan. Henry Burton describes his technique thus: "The handshake is the threshhold act, the beginning of politics. I've seen him do it two million times now, but I couldn't tell you how he does it, the right- handed part - the strength, quality and duration of it. I can however tell you a lot about what he does with his other hand. He is a genius with it. He might put it on your elbow or up by your biceps. He is interested in you, he is honoured to meet you. He'll share a laugh or a secret then - a light secret, not a real one... He'll flash that famous misty look of his. And he will mean it." That, to anyone who has met Bill Clinton, is Bill Clinton.

But where does truth end? Susan is more ruthless than even the most vicious renderings of Hillary. One night, she enters Burton/ Stephanopoulos's room - and not to talk tracking polls. Henry does his duty: "I'd never, I realised, made love before to a woman who used hairspray." Now that never happened. Hillary Clinton doesn't use hairspray - or does she? Only the last part of Primary Colors disappoints, a meander into the South that adds nothing. Otherwise, it's a hell of a book. But then Clinton's 1992 campaign was a hell of a campaign.