By Brian Wheeler
Political reporter, BBC News
The internet is fast becoming a key battleground in the race to be the next mayor of London.
Social networking offers politicians a whole new playground
The web offers a unique hotline to London's vast electorate, who also happen to be Britain's biggest users of the internet.
In a close-run contest in which every vote will count, the prize might just go to the candidate who makes the best use of it.
But the days when online campaigning largely boiled down to who had the best website are long gone.
The leading mayoral contenders have each developed sophisticated - and very different - strategies to make the most of the explosion in social networking and video sharing.
Their aides talk excitedly about Facebook, Twitter and YouTube - and how they are using e-mails and text messages to mobilise supporters across the capital.
Labour candidate Ken Livingstone has hired the US company behind Barack Obama's election campaign, Blue State Digital, to help him win a third term in office.
Obama's online campaigning and fundraising skills have been seen as a key factor in his emergence as the frontrunner for the Democratic nomination.
And although Mr Livingstone, with two terms in office under his belt, is starting from a very different position, his team are clearly hoping some of the Obama magic will rub off on their man.
"This election is neck and neck and we want to engage voters across the board and mobilise them into a massive effort to ensure Ken's supporters turn out to campaign in the run up to 1 May and then vote on the day," says a Livingstone spokesman.
An unofficial clip attacking Hillary Clinton was viewed by millions
"Online campaigning is not ever a replacement for street by street efforts, which is why our internet campaigning is all about using kenlivingstone.com to make it easier for supporters to get active and out into their local communities."
The internet suits Mr Livingstone's combative campaigning style - allowing him unlimited space to settle scores with rival candidates.
He recently used a YouTube video to hit back at Conservative candidate Boris Johnson's first party election broadcast - something that would not have been allowed on TV, with its strict rules on balance.
It also allows him to stress his perceived independence from the Labour Party machine - one of his traditional selling points to floating voters.
Ken Livingstone: 'A World Civilisation or a Clash of Civilisations - pt 1' - 12,866 hits (Jan 2007)
Boris Johnson: 'Johnson tackles a German' - 1,096,279 hits (May 2006)
Brian Paddick: '7/7 Bombings Police Timeline' - 2,243 hits (Nov 2006)
Ken Livingstone: 'Ken Livingstone on Boris Johnson' - 3,352 hits (Feb 2008)
Boris Johnson: 'Boris Johnson London Mayor First Interview' - 7,385 hits (Sep 2007)
Brian Paddick: 'BBC London News interview with Brian Paddick' - 1,774 hits (April 2008)
Mr Johnson is also running a highly personal campaign based around his own political "brand" - but the Conservative name is still prominent on the BackBoris homepage.
Casual visitors to the kenlivingstone.com home page would be hard pressed to work out which party the current mayor is representing. There is no mention of Labour - it is all about "Ken".
Mr Livingstone's strategists are clearly working on the assumption that party propaganda is the kiss of death on the internet, where maverick and independent voices are often valued above official sources.
That is why they are courting Labour bloggers with offers of access to information from the campaign team, interviews with Mr Livingstone and online adverts.
And like Obama in the US, the Livingstone campaign is using the internet to canvass for small donations from supporters.
Lib Dem candidate Brian Paddick has also turned to the US for inspiration, hiring influential liberal blogger Jerome Armstrong, who like the founders of Blue State Digital helped mastermind Democrat Howard Dean's pioneering 2004 campaign.
Mr Armstrong - sometimes dubbed the "blogfather" - will work with veteran US campaign strategist Rick Ridder, who helped Hillary Clinton win the Arizona primary.
Team Paddick are using the web to seek out voters in hard to reach places, who may have been turned off by the mainstream media's coverage of the race.
"It is not just an air war and a ground war it is a web war as well," says a spokesman.
Mr Paddick is already a creature of the net.
When he was a police commander in Lambeth, he was a regular contributor to radical website Urban75 under the name Brian: The Commander.
He incurred the wrath of the tabloids by confessing on the site that he could see the attraction of anarchism - but the controversy does not seem to have deterred him from taking part in online debates.
Aides say he is still in the habit of posting comments on discussion boards in the small hours of the morning.
"Brian is completely immersed in the web campaign. He is not like some politicians who can barely use e-mail," says an aide.
The Lib Dem candidate recently crossed swords with Mr Livingstone on The Guardian's Comment is Free site over funding for the London underground.
Green Party candidate Sian Berry, who is blogging her campaign on the New Statesman website, and George Galloway, who is standing for the London Assembly, also weighed in.
Boris Johnson was conspicuous by his absence. His campaign team insist he has better things to do than sit in front of a computer all day.
"We will rebut things that are untrue, but we are not going to be sitting there blogging with the other candidates all day, arguing with them in a random, unorganised way.
"We could do five visits across London, while they are sat behind a computer."
The Johnson campaign takes the web just as seriously as their rivals, but they began the race with a different set of challenges.
The 'Ken' brand is being pressed into service once again
The former Spectator editor was already a minor cult figure on the internet - thanks to his chat show appearances and outspoken journalism.
The trick was to convert that interest into something more concrete - by signing people up to online supporters network Team Boris, for example, which currently has more than 9,000 members.
"We say Boris is going to be in a certain area and when we get there, there is a really good group of people who have found out through Facebook or Twitter or by text message," says a campaign aide.
The Johnson campaign has also taken a different approach to advertising.
Paddick and Livingstone have both bought ads on Google - but Johnson has opted for the services of a search optimization firm (it seems to be working - type "London mayor" into Google and sixth link, behind the official mayoral sites and Mr Livingstone's Wikepedia entry, is BackBoris).
Johnson aides say money is tight - but they insist they will not be using the web to badger supporters for cash.
"We are not in the business of wanting from them all the time, our prime aim is to get our message across."
The smaller parties are also using the internet to full effect in the run up to 1 May.
The internet is the great leveller for candidates with tiny marketing budgets.
Clips on YouTube featuring UKIP's Gerard Batten, independent Winston Mackenzie, English Democrat Matt O'Connor, Left List candidate Lindsey German, Alan Craig, of the Christian People's Alliance or the BNP's Richard Barnbrook - get nearly as many page views as those from the big Westminster parties.
The bad news - for all the candidates - is that that normally amounts to a few hundred at most.
It may take an outrageous personal attack by one candidate on another or, more likely, a gaffe - what is known in the trade as a "Prescott punch" moment - before page views really take off.
The most popular Boris Johnson clip on YouTube, with more than a million page views, is a video of the Tory MP indulging in an over-enthusiastic tackle at a charity football match.
The most viewed Johnson video relating to the mayoral contest comes in at a more modest 7,385 hits.
A video which Labour claim shows him being caught out over the cost of his plans for new Routemaster buses - it was filmed by a Labour activist on a mobile phone - had 74 viewings in its first 17 hours on the site.
The most viewed Ken Livingstone clip, with about 12,000 hits, is some shaky footage of his contribution to a debate on Western civilization and jihad, followed by an old video from Channel 4 comedy show TriggerHappy TV.
His most viewed mayoral campaign clip is an interview with The Guardian's Michael White, which has been seen by 3,352 people.
The most viewed Brian Paddick clip on YouTube is of the then Deputy Assistant Commissioner of the Metropolitan Police giving a press conference in the aftermath of the London bombings on 7 July, 2005, which has been seen by 2,243 people, followed closely by a BBC London interview on the mayoral contest.
In the US Democratic race, a film portraying Hillary Clinton as a totalitarian dictator has been viewed more than 5 million times.
It was reportedly created by a "rogue" employee of Blue State Media and swiftly disowned by the both the company and the Obama camp.
But as an illustration of the power of the internet to wound a political opponent it was hard to beat - and very easy to emulate...