Howard Dean's popularity is all about being the outsider.
His supporters despise the traditional "sell it as soap powder" kind of political campaign. They love his unpolished conversational speeches and his willingness to stray into the long grass where other politicians fear to run.
In short, Mr Dean never looked comfortable as the front-runner. And when that happens, a candidate doesn't stay in the front for long.
The Dean Scream encapsulates why so many love him, and why he makes others so nervous
The problem with Mr Dean's strategy is that what appeals to his supporters is precisely what makes other Democrats nervous.
He doesn't seem presidential. He doesn't control his temper. I can't see him beating Bush. He puts his foot in his mouth.
All these things were said to me on the campaign trail this week by New Hampshire Democrats.
The Dean Scream in Iowa sent shivers down many a Democratic spine. But the problem has always been there.
He says he's going to attract so many people who'd never taken an interest in politics before, he will create a new majority. But these people failed to materialise in Iowa. And they didn't come out for him either in New Hampshire.
So now Mr Dean returns to his role as the underdog. He and his team can use the internet, their decentralised campaign structure to operate a hit and run insurgency against John Kerry.
That's all fine. But it's not going to help Mr Dean's chances of becoming the front runner. Sooner or later, every guerrilla leader has to take off his khakis and sit down and do business with the Establishment if he wants to become president instead of sniping at it.
Democrats know that and that is why they have been supporting John Kerry. He's not the best loved candidate, but he feels stable and secure.
Mr Kerry won New Hampshire by following the Clinton playbook. He listened to people. And he never gave up.
Bill Clinton would carry on talking to voters until the last one got up to go home. He drew energy from the crowds. It doesn't come so naturally to John Kerry. But he's making a very good stab at it.
Can Kerry translate his warmth on the campaign trail to the mass media?
In New Hampshire, despite four hours sleep a night and an endless diet of spaghetti, he looked relaxed and genuinely happy to be on stage. He even laughed at himself and let his stepson do wicked impersonations of past presidents. He seemed to be enjoying himself and the crowds responded.
Mass media appeal?
But from now on, the campaign is nationwide.
Instead of going to see a candidate in the local fire station, the nearest that most Democrats will get to these people is on the TV screen in their living rooms, and at long range John Kerry can look aloof and Al Gore-like.
His test will be whether he can transfer his new-found warmth to the mass media.
Lessons learnt from New Hampshire: The Iraq War comes second to electability for Democrats. Mr Kerry's support for the war has not been a significant handicap so far.
Wes Clark is not getting traction. He avoided Iowa and sunk all his time and most of his advertising budget into New Hampshire - and still came third.
John Edwards may well win a state before Howard Dean does.
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