Vote Colbert! (the candidate running for both parties)

US politics is ripe for ridicule, and Stephen Colbert, one of the country's most subversive comedians, has taken up the challenge. He has announced a Presidential campaign -for both Democrats and Republicans

There are candidates for the American presidency who like to tease the electorate for months or even years about their intentions. Candidates like Fred Thompson, the former senator turned television actor, who threw his hat into the ring last month; or Al Gore, the man who came within a few hanging chad of the White House in 2000 and still refuses to rule out another presidential run completely.

And then there are candidates like Stephen Colbert, who tease their supporters not so much because they want to keep them in suspense, but because teasing is what they do for a living.

Colbert is not a politician. He doesn't even play one on TV. He's a satirical comedian, the host of the outrageously successful Colbert Report, which airs nightly on Comedy Central and enjoys a cult following much like the spoof newscast that precedes it, The Daily Show.

For the past two years, Colbert – pronouncing his name, French style, with a silent "t" – has revelled in the role of a blowhard conservative talking head, who doesn't know a whole lot but doesn't let that stop him from expressing his opinions with a boneheaded insistence mixed with boundless vanity. The act has won him awards, an adoring audience and – infamously – a spot giving the keynote speech at last year's White House Correspondents' dinner, in which he turned the screws mercilessly on the White House press corps and on George Bush, who was sitting just a few feet away from him.

Now he's taken his sly, delightfully subversive take on modern America to the next level, by announcing that he's running for the presidency in his home state of South Carolina – on both the Republican and the Democratic tickets. In the process, he's managing to do what he does best – skewering all the most absurd aspects of American politics, from the quid-pro-quo fund-raising, to the fake impieties of invoking God at every turn, to the shallow vanity of the candidates and their even shallower adherence to real public policy positions.

Running for president is certainly a risk. Already, the complaints have begun that he is demeaning the cornerstone of America's electoral democracy and drawing undue attention to himself and his latest book, I Am America (And So Can You!). But it's also an irresistible challenge – to stay funny, and withering, and appreciated by his audience from now until the South Carolina primary on 26 January.

So far, he's been on rare form. Admittedly, he's been hinting at a White House run for weeks and sharpening his barbs in careful preparation. As he wrote in a tongue-in-cheek op ed column for The New York Times just last weekend: "I am not ready to announce yet – even though it's clear that the voters are desperate for a white, male, middle-aged, Jesus-trumpeting alternative."

As he also wrote in The Times: "I don't intend to tease you for weeks the way [former Republican House Speaker] Newt Gingrich did, saying that if his supporters raised $30m (£15m), he would run for president. I would run for $15m. Cash."

Until this week, the tease was regarded by his fans as little more than a gag. Of course Colbert would flatter himself into thinking his audience wanted him to run. It was all part of his persona. But then he actually announced on his show on Tuesday night.

He started, in fact, a few minutes before his show started, by appearing as a guest on The Daily Show – where he worked as a correspondent, and developed his Colbert alter ego for eight years before branching out on his own. Colbert came into The Daily Show studio on a bicycle ridden by a man in an Uncle Sam hat, and sat down with a bale of hay and a beer to give himself a man-of-the-people feel. He then told The Daily Show's host, Jon Stewart, said that he had "decided to officially consider whether or not I will announce". By the time his own show rolled around, his mind was made up. "After nearly 15 minutes of soul-searching, I have heard the call," he said.

As a giant legend appeared on the screen – "I'm doing it!" – red, white and blue balloons rained down on a beaming Colbert. He then turned to a prominent television political analyst, Jeff Greenfield (a very funny man in his own right), and asked him to assess his impact on the 2008 race "in the past three minutes". Greenfield called it "astounding".

Anyone watching the show could have been forgiven for thinking it was all still a joke. But it turns out it is not. The next day, the head of the South Carolina Democratic Party revealed that Colbert's people had begun asking him about the viability of his candidacy about three weeks ago, and appeared serious about getting him on the ballot. The head of the state Republicans similarly disclosed that if Colbert paid his filing fees there was nothing he could do to stop him running – even if he was already on the other party's ticket.

Neither party is remotely pleased about this turn of events. Joe Werner, the executive director of the South Carolina Democrats, told reporters his board would have problems with his candidacy, especially if he was running as a Republican at the same time. Katon Dawson of the Republicans, meanwhile, told The New York Times: "My advice is that he could probably have more fun buying a sports car and getting a girlfriend."

There are, of course, precedents to Colbert's spoof candidacy. A comedian called Pat Paulsen ran for president six times between 1968 and 1996, and made his repeat candidacies part of his stand-up act. In Britain, we are more than familiar with Screaming Lord Sutch and the Monster Raving Loony Party. What makes Colbert different – and a whole lot more intriguing – is that he is a cult figure whose comedy has been overtly political from the get-go.

He, like Jon Stewart, knows that American politics is in a state of degradation ripe for lampooning. Between them, they have made an extraordinarily good living doing just that. In other words, there's a real chance he might get significant numbers of votes. The best point of comparison, in fact, may not be Screaming Lord Sutch but rather Cicciolina, the Italian porn starlet who was sponsored as a parliamentary candidate by a small, renegade party in the 1990s to show up the shallowness and corruption of the system as a whole, and – much to everyone's surprise and embarrassment – ended up winning.

Even before this week, college students across the country were sporting Stewart/Colbert 2008 badges and bumper stickers on their car. On his show, Colbert took great pleasure in taking out a Stewart/Colbert sticker, tearing off the Stewart part and tossing out joke names for possible vice presidential running mates. Now, on the social networking internet site Facebook, fans have set up a "Million Strong for Stephen T Colbert" group in imitation of the "One Million Strong For Barack" group established for Barack Obama. Colbert's group had 5,000 members by 5pm on Wednesday and more than triple that by midnight.

All this is heady stuff for a comic actor with a flare for improv who has worked his way up the television ladder for the past 20 years. Now 43, Colbert trained with Chicago's famed Second City theatre troupe, then wrote and performed on the Dana Carvey show and other television comedies before landing on The Daily Show the year it launched in 1997. It was there that he honed the Colbert persona, taking his inspiration from the screaming heads on Rupert Murdoch's unapologetically conservative Fox News network – people like Bill O'Reilly, who parades something he calls the "No Spin Zone" to spin the news his way, and Sean Hannity, who specialises in humiliating and silencing guests he happens to disagree with.

By the time The Colbert Report (the "t" in "Report" being as silent as the one in his name) launched in October 2005, the country was both overladen with maximum-volume right-wing commentators and also seriously questioning the competence of the Bush administration in the wake of Hurricane Katrina and the ever-deteriorating mess in Iraq.

On his first show, Colbert talked about something called "truthiness" to describe things he and his fellow conservatives fervently believe to be the case regardless of what the facts are. It was a brilliant commentary on the White House's scorn for what it has called the "reality-based community". Quickly, "truthiness" was declared the most memorable new word of the year by both the American Dialect Society and the Merriam-Webster dictionary.

Highlights since then have included interviewing a right-wing Christian congressman from Georgia who was forced to admit on camera he couldn't remember the Ten Commandments, even though he wants them posted in schools and public buildings across the country, and inviting Gloria Steinem and Jane Fonda to make apple pie in his studio while talking about why the feminist movement has lost its way.

His White House Correspondents' dinner speech is probably the most celebrated single piece of satire to emerge from the Bush years. Pooh-poohing critics who said at the time the administration was rearranging deck chairs on the Titanic, Colbert deadpanned: "This administration is not sinking. This administration is soaring. If anything, they are rearranging the deck chairs on the Hindenburg!"

If nothing else, Colbert's presidential run promises to be highly entertaining. "What do I offer?" he wrote in his Times column. "Hope for the common man. Because I am not the Anointed or the Inevitable. I am just an Average Joe like you – if you have a TV show."