PAWLEYS ISLAND, S.C. Stephen Colbert came home to South Carolina last weekend to kick off his campaign for president. More than 1,000 supporters showed up at a rally in Columbia, the state capital. The mayor called him the state's "favorite son," gave him a key to the city and proclaimed the occasion Stephen Colbert Day.

All pretty standard political fare except for one thing. Colbert is a comedian, he runs a show on Comedy Central featuring a right-wing blowhard roughly modeled on Bill O'Reilly. He promised the crowd that if elected he would "crush" the neighboring state of Georgia. "Our peaches are more numerous than Georgia's," he asserted, sinking rapidly into gutter politics. "They are more juiciful."

So it's all a big joke, right? Not quite. Yes, Colbert is trying to sell his new book. And no, he's not a serious candidate. But he is a serious commentator, part of a great tradition of jesters, cartoonists and satirists who have always poked fun at established leaders and punctured their carefully crafted self-portraits.

His signature concept is "truthiness," defined as something that you want to be true, even if it's not (named "word of the year" by Merriam-Webster in 2006). Does "Mission Accomplished" come to mind? Or "Brownie, you're doing a heck of a job?"

Colbert has plenty of material to work with. Here's what he said announcing his campaign: "I am from South Carolina. I am for South Carolina. And I defy any other candidate to pander more to the people of South Carolina, those beautiful, beautiful people."

Reading those words, you can't help thinking of Rudy Giuliani, a lifelong Yankee fan donning a Red Sox hat just in time for the World Series. Or Hillary Clinton, abandoning the Cubs for the Yanks. And what about those candidates who practically drink ethanol for breakfast while courting those "beautiful, beautiful people" in Iowa?

Clearly Colbert is catching on. A pro-Colbert group started on the social networking site Facebook (by a 16-year-old from Alabama) attracted 750,000 members in less than a week, double the number who signed up with Barack Obama over eight months. By last weekend the number had reached 1.13 million. The Web site was so overloaded it briefly suspended operations.

In a poll by Public Opinion Strategies, Colbert drew 2.3 percent of Democratic voters, just behind Joe Biden and ahead of Bill Richardson and Chris Dodd. In a survey by Rasmussen Reports, 13 percent said they'd choose Colbert in a three-way race with Clinton and Giuliani. That led Deborah Netburn, TV critic of the Los Angeles Times, to wonder: "Has America lost its collective mind?"

The answer is no. Tim Russert interviewed Colbert on "Meet the Press," and elicited this comment: "I think the country is facing unprecedented challenges in the future and I think that the junctures that we face are both critical and unforeseen, and the real challenge is how we will respond to these junctures be they unprecedented or unforeseen, or God help us, critical."

Remember, the first baby boomer just retired, a tiny trickle foreshadowing a tidal wave that is about to swamp Social Security. Yet what most candidates say about fixing that problem is indistinguishable from Colbert's answer. So who's the fool here?

"Stephen has an incredible following," says Joe Werner, head of South Carolina's Democratic Party, "I'm a fan of the show." He's not alone, particularly among young people. Of Colbert's regular audience of about 1.3 million, a quarter are under 30, and two-thirds are under 50. (Countless others watch clips on YouTube or e-mailed videos.)

Browsing through various message boards over the last few days gives a real sense of what these fans see in Colbert (and his pal Jon Stewart, who hosts "The Daily Show" just ahead of his on Comedy Central). They cut through the garbage, they expose hypocrisy, and, in a phrase from the 60s, they "tell it like it is."

Don from Columbia posted this message on CNN after attending the Colbert rally: "Colbert is not a nut. Anyone who says that does not pay attention. He and John Stuart (sic) are probably the two most honest men in 'media' these days. Colbert is exciting young voters who will make a serious choice down the line." Added Drew from Kent, Ohio: "Since there's no real candidates who are willing to stand up for us than sure, I'll take a comedian."

Stephen Colbert is a fake candidate but a real critic. In other words, he's a real fake. And that's the truthiness.

Steve Roberts' latest book is "My Fathers' Houses: Memoir of a Family" (William Morrow, 2005). Steve and Cokie Roberts can be contacted by e-mail at stevecokie@gmail.com.