TO THE front-runners in the race for the Republican nomination, Ron Paul is a joke. The Congressman from Texas is portrayed as a political outsider who once stood against Frank Zappa in the Libertarian Party primary, a barmy radical with no hope of influencing policy, much less mounting a serious challenge for the presidency.

Never mind that in seven televised Republican debates, Paul has won the online and text message vote six times, nor that his YouTube channel has more subscribers than leading Democrats Barack Obama and Hillary Clinton.

In telephone polling of Republicans, which is still perceived as the only meaningful way to gauge potential primary votes, he has yet to break through the 5% barrier, placing him a distant sixth in a field of eight.

But Mitt Romney, Rudy Giuliani, John McCain and Fred Thompson were forced to take Paul's candidacy seriously last week when his supporters raised campaign donations worth $4.2 million in a single day, the most successful Republican fundraising drive of the 2008 election cycle.

The November 5 event was described in online appeals as a "money bomb", deliberately linking it to the plot to blow up the British parliament in 1605. Afterwards, spokesman Jesse Benton clarified that Paul is no Guy Fawkes and doesn't support bombing government buildings: "He wants to demolish things like the Department of Education, but we can do that very peacefully, in a constructive manner."

Paul's platform is founded on lifelong opposition to big government. He favours drastic reductions in federal taxation and spending, abolishing income tax entirely, returning to the gold standard to stabilise the dollar, bringing troops home from Iraq and adopting a foreign policy of non-intervention whenever possible.

When he stood for president in 1988 as the Libertarian Party candidate, he won just 0.47% of the vote. But disillusionment with America's political system is such that his message of fiscal prudence and withdrawal from military engagements overseas is finding unlikely new converts.

Paul describes his principles as "old, old-right positions of the 1950s" but in espousing them he has tapped into a younger demographic largely lost to his Republican rivals, as evidenced by his huge online supporter base and the teenagers wearing "Ron Paul revolution" T-shirts who attend his rallies.

Party strategists dismiss this as negative appeal that will not translate into votes. Responding to the record day of donations, Republican consultant Frank Lutz told Time Magazine that Paul's supporters "just like him because he's the most anti-establishment of all the candidates, the most likely to look at the camera during the debates and say, Hey, Washington, f*** you'."

The language doesn't suit Paul, an unfailingly courteous retired obstetrician, but his voting record in the House of Representatives is indeed one of intractable opposition to anything he perceives to be unconstitutional. He has been the lone dissenter in numerous votes, from a resolution to censure the Sudanese government over genocide in Darfur to a proposal to award Rosa Parks a golden Congressional medal.

He also believes that the US should withdraw not only from Iraq, but from Nato and the United Nations.

After a 1960s tour of duty as a flight surgeon with the US air force, Paul took over a doctor's practice in Lake Jackson, Texas, eventually delivering more than 4000 babies. He was first elected to Congress in 1976, was re-elected by his district three times, and lost an attempted Senate run in 1984. He returned in 1996 and has been a member of the House ever since.

When Jon Stewart interviewed Paul on the Daily Show, he observed "you appear to have a consistent principled integrity. Americans don't usually go for that".

The chances are that despite his growing campaign budget, Paul will be outmanoeuvred by Giuliani, Romney or McCain in the early primaries, much like Howard Dean in 2004, the last candidate to inspire extreme online devotion with a passionate rejection of the political status quo.

Democrats will hope that Paul then runs as an independent, splitting the conservative vote, just as Ralph Nader took crucial ballots from Al Gore in 2000.