Vice-President Al Gore was supposed to have a clear run for the Democratic nomination in 2000 after serving eight years as a loyal No 2 to President Bill Clinton.

The most likely rival for the nomination was seen as the Democratic minority leader in the House of Representatives, Dick Gephardt, who has strong support in the labour movement and is popular with his party members in the House.

Gephardt dropped out after sizing up Gore's apparently impregnable position as Vice-President, setting his sights on becoming Speaker of the House if the Democrats can win a majority there next November.

Little notice was taken when a former senator, Bill Bradley from New Jersey, began to campaign for the Democratic nomination last spring. Gore and his campaign ignored Bradley and concentrated on attacking his presumed Republican opponent, Governor George W. Bush of Texas.

But the low-key campaign by the 56-year-old Bradley, who also showed formidable fund-raising powers, caught the Gore campaign by surprise. By the end of the summer, Gore's poll ratings had slumped and Bradley was catching up.

Gore found he was a victim of "Clinton fatigue" as many Democrats viewed him as an extension of a Presidency tainted by the Monica Lewinsky saga. Gore was also seen as a humourless, technocratic figure, where Bradley - a former basketball star as well as Rhodes scholar at Oxford - was more prepared to listen than to preach.

With the US enjoying unprecedented prosperity, Bradley's message is that it is time for a leader with a new vision who can spread some of the riches among the less fortunate. He proposes a universal healthcare system which will bring in the 45 million Americans who are without health insurance.

Gore has had to stop campaigning as if he were the presidential candidate and follow Bradley in appealing to traditional Democratic interest groups such as bluecollar workers, teachers, housewives and African-Americans. Gore, who is five years younger, has also tried to loosen up and get rid of his image as wooden and boring. He has also personalised his campaign by telling his "story" as a boy in Tennessee, a troubled soldier in Vietnam, a theology student and journalist before following his father into politics.

As the Vice-President, Gore has worked hard at winning endorsements from leading figures in the Democratic establishment. Thus while Bradley had to start from scratch in the primaries to win the votes of delegates to the Democratic convention next August in Los Angeles, Gore has already sewn up most of the so-called "superdelegates". These are the governors, senators, members of Congress and party officials who are automatically entitled to vote at the convention.

But how solid these superdelegate votes for Gore are remains to be seen, especially if Bradley can start a landslide in his favour by winning the primaries in New Hampshire, New York and California by mid-March.

The clashes between Gore and Bradley have become sharper as the New Hampshire primary draws nearer. Their most recent debate this week saw Bradley for the first time making references to scandals in the Clinton-Gore administration. Gore has riled the Bradley campaign by challenging the costs of his opponent's health insurance scheme.

But civility between the two men is being maintained, at least on the surface. They both support freedom of choice for women and open toleration of gays in the military.

But Gore's strength among African-American voters, especially in the southern states, is a disappointment for Bradley, who has made racial equality one of his main priorities since he entered politics. Gore's appeal to women voters is not so impressive, and this weakness is a serious concern for his campaign. President Clinton won both his elections with strong support from middle-class women voters who now seem to be tilting towards Bradley.

If Gore does badly in New Hampshire, his campaign will be in trouble but not yet terminal. California on March 7th will be vital for him as Bradley is expected to win New York where he played for the famous Knicks in the 1970s. It will be all over on March 14th when the big southern states vote. If Gore is still in the race by then, he should be able to repulse the Bradley challenge.