Wired on Friday For the past few months, I have been tracking the rise (and rise) of Dr Howard Dean of Vermont, the frontrunner in the nominations for Democratic presidential candidate.

The US elections are still more than a year away but, with much riding on the result and a great deal of rancour of both sides, attention is being placed, much earlier than usual, on Bush's potential adversary.

I'm not a political expert - especially not on US politics. But Dr Dean's campaign has fallen into my purview because it's been driven largely by the internet.

Presidential candidates in the US have a long, hard struggle to the top. The parties - Republican and Democrat - are not the rigid hierarchies one would expect. They're more like giant, expensive and idling machines - dozens of committees with certain functions but without a centrally controlled core.

That core comes from the campaign teams of whichever candidate wins the primaries. Next August, the Democrats will have selected their presidential candidate and his team will be dropped into the very top of a party machine.

Usually that team is a small group of hardened political professionals. For Dr Dean, however, the team has opened up the process. His campaign manager, Joe Trippe, early on decided to publicise every detail of the campaign on a website, complete with a little area for comments.

That small step has had powerful consequences for the campaign. In the comments section, Dr Dean's earliest supporters were able to talk to each other. Using another website, meetup.com, they arranged and publicised local meetings. And through Dr Dean's website, they collected and sent donations - and kept an eye on how much money Dr Dean had gathered to date.

These simple tools have catapulted Dr Dean from an fringe candidate to the leading Democratic contender. His fund-raising, largely collected from more than 70,000 small donaters rather than a few large organisations, has brought in millions of dollars. His supporters, who now number more than 350,000, have worked to distribute clips of his speeches, and organise stalls and leafleting at public events.

I tagged along to a Dr Dean meet-up in June. It was at a local cafe, whose owners were very surprised to find themselves hosting around 80 enthusiastic coffee-drinkers. Many of the attendees had never supported a political candidate before. Many spoke of their relief at finding others who shared their worries about the Iraq war and the economy (Dr Dean first came to prominence as the only Democratic candidate to publicly come out against the war).

The meet-up organisers had received from Dr Dean's headquarters a mailing list of registered Democrats in New Hampshire. The drawn-out mechanics of the primary election process means that results in the earliest primaries, such as New Hampshire, can have a strong influence on who are perceived to be the leading candidates.

Dr Dean's team asked the volunteers if they'd write a personal letter to two or three of these floating voters.

Over the next few days, many thousands of voters in New Hampshire received handfuls of letters from their fellow voters across the US, giving personal reasons for their choice of candidate. The latest figures show that Dr Dean has a 21 per cent lead over his nearest competition in the state. A few months ago, no-one had heard of him.

Since that local meet-up, attendance has increased. There are now three separate meetings in the area - all of which have attendance greater than the one I attended. The Dean campaign aims to collect a million supporters for its campaign by the end of the year - and are on track to reach that figure.

It's an astounding testament to the power of using the Net to organise. It's a rewarding result for Joe Trippe, who admitted that, when he first agreed to a Net campaign, he was scared of releasing so much control to such a wide group of people. The contrast to the traditional, tightly planned, militarily executed publicity drive of most modern political campaigns only highlights the unorthodox success of the ploy.

But how far can it go? A hundred thousand volunteers is an order or so larger than any Democratic candidate has ever had at this stage. Reading the Dean internet discussion forums, you get a whiff of how heady being part of such a growing movement can be.

But when I spent some time working behind a Dean stall last month, crammed between two scientologist stands at San Jose's local fair, it dawned on me what a long ride it is from a million well-wishers and winning over a majority of the American people. The stall was well attended and well organised. But almost no-one who came to the stall knew that Dr Dean was even a candidate. And the contrast between the Dean supporters at the table - white, geeky, worried - and the majority of the passers-by - multi-cultured, out with their families and largely unconcerned with politics - was stark.

A hundred thousand people is a vast volunteer network. You could spend your life talking politics within a group like that, working and consulting and arguing, without ever meeting someone who disagreed with you. This is particularly true on the Web, where reading the Dean blog it's clear that many are spending much of their time posting and responding to other supporters' discussions.

For those who came to Dean to be reassured that others felt the same way about politics as they did, this will be enough. But, to win an election, the Deanites are going to have to do more than just hope that forwarding mail can lead to victory.