Stephen Colbert, the faux right-wing host of Comedy Central’s “The Colbert Report,” has struck comedic gold insisting his ratings-getting candidacy for president — as both a Republican and a Democrat in, um, only South Carolina, with Larry Craig as potential veep — is dead serious. Turns out, though, the Federal Election Commission might not think it’s a joke.

If Colbert keeps up the shtick, he could violate federal law. The FEC prohibits corporations from contributing “anything of value” to campaigns — including airtime. Whenever Colbert promotes himself on “The Report,” it could be an illegal in-kind contribution from Comedy Central. The Federal Communication Commission also has an equal time law, which says TV stations must offer candidates equal airtime. Theoretically, the 16 remaining candidates could demand parity for Colbert’s 30 minutes a night, four days a week, plus twice-daily reruns. (NBC decided earlier this year to stop airing “Law & Order” reruns featuring Fred Thompson for that very reason.)

If push came to shove, Colbert would probably concede like Howard Stern did before the FCC could quash him in the 1994 New York gubernatorial race. But the Center for Responsive Politics’ Massie Ritsch warns that the FEC “doesn’t have a great sense of humor.”

Nor has Colbert dialed it down. He made a mockery of “Meet the Press” last Sunday, addressing the “realness” factor of his campaign: “This is not a dream, OK? You’re not going to wake up from this, OK? I’m far realer than Sam Brownback, let me put it that way.” His Web site has posted downloadable petitions to get him on the ballot in South Carolina. And his popularity has rocketed: A Rasmussen poll found in a three-way race with Hillary Clinton and Rudy Giuliani, Colbert would get 13 percent of the vote. A Facebook group called “1,000,000 Strong for Stephen T Colbert” hit 900,000 members in one week, crushing Barack Obama’s group of 380,000 after eight months.

To qualify as a candidate, you must raise or spend $5,000. Colbert has done neither, but the lawyerly consensus is that he risks ruffling FEC feathers by just having an effect on the election. When he does (and he may already), the boxes running through Colbert’s head could go from ballot to Pandora’s.