Candidates McCain and Obama have both appeared alongside Stewart
The US presidential election is a deadly serious business, as the party conventions amply illustrate.
Which might make it surprising that satire is playing a more and more influential role in the way the US media covers politics.
Jon Stewart, presenter of The Daily Show, produced by Comedy Central, attracts a key youthful audience and has all the top politicians as guests.
The show tackles political topics in a humorous way. It makes fun of the way politicians contradict themselves, and also lampoons the mainstream news networks' overblown style with its own team of anarchic correspondents.
Jon Stewart, a former stand-up comedian, is the main presenter and lynchpin. But as far as the audience is concerned, there seems to be more to the show than having a laugh.
"Is Jon Stewart the most trusted man in America?" ran a recent New York Times headline, reporting survey evidence that suggests he is now seen in the same light as the more traditional news anchors like Tom Brokaw of NBC news.
NBC's Tom Brokaw acknowledges Stewart's remarkable appeal
Brokaw told me he especially admires Stewart's appeal to younger viewers - those the politicians and mainstream media find hardest to reach.
"To Jon's great credit, he has drawn the new generations into the political arena in a way they have not been for the last few election cycles, and the country is better off for it".
Philip Bobbitt, a veteran political commentator and academic, became a fan after observing Stewart's popularity amongst his students.
"I think he feels he has a constituency of young people to whom he feels a responsibility and he is trying to present issues in a satirical way but in a robust and affirmative way".
So what lies behind Stewart's appeal across the generations?
He is now in his mid-forties. But Larry Nicol, one of his schoolteachers in New York in the 1970s, recalls lessons with Stewart in the classroom as a kind of rehearsal for his later comic career.
"The class was basically like a bunch of guys sitting around on a Saturday night, having a beer and making funny wisecracks," he said.
"To be a psychologist - which he majored in at university - and then switch to comedy, you have to have that veneer of political awareness, and he did have a passion to be funny."
But such passions, as many a would-be performer knows, do not pay the bills.
LISTEN TO THE PROGRAMME
After Stewart graduated, he worked as everything from puppeteer to Woolworths' shelf-stacker while trying to become a comedian - encouraged, with some anxiety, by his mother Marian Leibowitz.
"He made a little deal with me that I would give him two years to try and explore what he wanted to do," she says.
"So he took all kinds of weird jobs just to keep himself afloat until that point he announced he wanted to go to New York to be in comedy."
Stewart finally found his feet in stand-up comedy, and then moved into TV presenting via MTV in the late 1990s.
His humour is biting, especially when you don't know what to expect. This is a very smart, serious fellow
John Zogby, political pollster
As presenter, Stewart relishes the laughs he gets as politicians' inconsistencies are mercilessly exposed by slick editing, and the main news anchors are parodied with hyped-up language.
But unlike other satirical shows, Stewart also secures top political players. Bill Clinton has been on, as has Pervez Musharaff.
While he was Pakistani president, he held a surreal tea-time conversation with Stewart about the whereabouts of Osama Bin Laden.
And Barack Obama and John McCain, desperate to appear cool to younger voters, have joined Jon Stewart for what they hope is an electorally beneficial laugh.
But these are not casual appearances where the candidates can relax and wander humorously off-message. Stewart's interviews are based on detailed research, and he can be forensic as well as funny, as John McCain discovered when confronted over US policy in Iraq.
John Zogby, top US pollster and adviser to many politicians, admits he has been "skewered" on Stewart's show.
"His humour is biting, especially when you don't know what to expect. This is a very smart, serious fellow."
Stewart likes to protest that such skewering is purely for comic effect.
And yet he has passionate views about what he sees as the failure of other kinds of news debate to shed light on political issues.
He famously confronted the hosts of CNN's crossfire programme, accusing them of "partisan hackery" and "doing theatre when you should be doing debate".
And what of Jon Stewart's future? Some have assumed that satire will struggle in the post-Bush era.
But Stewart, the iconoclast in danger of becoming an institution, will prosper as long as the politicians, as well as TV advertisers, crave that appeal to youthful cool.
Some suggest he will be offered huge amounts to sign up as a presenter with one of the major US networks.
Jon Stewart as a mainstream broadcaster, avuncular informant of the American nation? "Are you insane?" is a favourite catchphrase Stewart might use in response to such a suggestion.
But the journey from hard-up amateur comedian to millionaire media icon has, in its way, been insanely swift. One way or another Stewart, a man very much in demand, is likely to have the last laugh.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.