The power of fake news.

Midway through The Daily Show's coverage of the September 30 presidential debate, the host, Jon Stewart, called on his "correspondents in the field for some in-depth analysis.

"Ed, how are the Kerry people feeling?"

"Ecstatic, Jon," came the reply. "Kerry's people couldn't be happier. Their candidate went up against a sitting war President who's never lost a debate and held his own." "OK," said Stewart. "And Rob, what's the mood at the Bush camp?"

"Triumph, Jon," the correspondent said. "Their man faced off against John Kerry, a golden-tongued virtuoso of words and captain of the Yale debate team. He's been honing his oratorical skills since the age of 3, and the way they see it, by not allowing himself to be reduced to tears, the President was the big winner tonight."

This exchange was a clever takeoff on both the shallowness of campaign spin and of the news media's capacity for buying into that spin. It ran on Comedy Central while the real spin doctors were toiling away on other networks.

"Fake news" is the comedy catchphrase of the moment, and it doesn't apply just to The Daily Show. HBO's Ali G uses a talk-show format to mock politicians who are unaware that the whole show is a gag, while humorist Andy Borowitz files fake stories in perfect newspaper prose on BorowitzReport.com. The Onion, a phony newspaper, has a growing readership, and the bogus "Weekend Update" is a perennial favorite on Saturday Night Live.

GOING MAINSTREAM

The current boom in fake news has even prompted some mainstream news outlets to include news satire in their real news programming. ABC's Primetime Live now closes with a two-minute musical rendition of satirical headlines. Mo Rocca, formerly of The Daily Show, played a wisecracking on-air correspondent on CNN's Larry King Live during the political conventions. And Borowitz, a regular on CNN, appears alongside legal experts on Court TV.

"I spent an hour on Court TV talking about the [Scott and Laci] Peterson case, and I don't know anything about the Peterson case," says Borowitz. "It's perfectly appropriate on mainstream news shows now to have a satirist in the mix."

Most satirists say the popularity of fake news reflects a polarized electorate that suspects the media of doing the other side's bidding, coupled with recent high-profile journalistic scandals such as reporters' having been fired from The New York Times and USA Today for plagiarism.

MOCKING THE MESSENGER

Perhaps feeling let down by the mainstream media, 21 percent of people under 30 say they learned about the 2004 campaign from sources like The Daily Show and late-night television monologues, up from 9 percent in 2000, according to a Pew Research Center study released in January.

"The premise of any joke delivered by oddball newscasters is that they're making fun of the media's treatment of news as much as they are the subjects of the news," says Rocca.

Of course no self-respecting satirist would take credit for anything so profound as affecting political discourse, or even admit to having a political point of view. "We have no agenda other than holding on to our cushy, high-paying basic-cable jobs," says Ben Karlin, The Daily Show's executive producer.

News satire is a time-tested gag. Mark Twain wrote fake news stories, and television has produced a steady stream of news spoofs. But even the satirists themselves are surprised by the sudden upsurge in the market for their craft.

A SAVVY AUDIENCE

Karlin doubts that a fifth of young Americans rely on fake news for most of their political information. For one thing, he says the audience could not possibly get the jokes if it did not already know about the news stories that were being spoofed. And The Daily Show mocks not just the style of the news but also journalistic conventions, like the media's fixation with fairness.

Once they have the audience's sympathies, purveyors of fake news, like all comedians, have a simple task: Be funny. According to Rocca, "A well-told joke that has a Republican target, if it's clever enough, gets Republicans to laugh, too."

Warren St. John, a reporter for The New York Times, writes often about media and entertainment.