Mauling stalls the former favourite

To Howard Dean's campaign manager, Joe Trippi, the dashed hopes of the Iowa caucus look unnervingly like history repeating itself. In 1984, Mr Trippi was working for Gary Hart, another underdog candidate willing to break all the rules of presidential campaigning.

Looking back now, Hart would almost certainly have given Ronald Reagan a tougher run for his money than the eventual nominee, Walter Mondale. But Hart made the Democratic Party establishment nervous, failed to translate the grass-roots movement behind him into primary triumphs, and he fizzled and crashed.

Theoretically, at least, Mr Dean has understood the Gary Hart problem and gone a long way to counter it. He has had the internet as an organising tool, has build a grassroots movement more than 500,000 strong, and has raised $40 million to date, way more than any other Democratic contender.

Mr Dean has also done an effective job of attracting endorsements, including Al Gore, and he has more than 40 members of Congress on his side including the leaders of the black and Latino congressional caucuses.

So why did it all go wrong? How did the underdog turned front-runner suddenly stumble so badly? Mr Dean's supporters are convinced it is because of the mauling he has received, at the hands of his fellow candidates and also in the media.

He has been depicted as a gaffe-prone, tub-thumping populist with no chance of being elected.

The supporters are right to complain that Mr Dean - a politician so centrist when he was governor of Vermont that he was regularly accused of acting like a Republican - has been miscast as an angry left-liberal out of sympathy of the US mainstream.

But there are other issues. Mr Dean goes against the mainstream of US politics by being so blunt, and that makes voters and party operatives nervous. In Iowa, he broke one of his own rules by going negative in the final few days, especially against his perceived challenger, Richard Gephardt, who ended up going down in flames.

The astonishing momentum that took him so far is now halted, and he cannot afford to lose his lead in New Hampshire. Mr Dean's campaign says it will now stop the negativity and revert to the core message that attracted supporters in the first place. It remains to be seen whether that message gets distorted, or simply ignored, as the primary battle progresses.