Running for president is no joke.

John McCain knows that. So does John Edwards. As do Hillary Clinton, Barack Obama, Mitt Romney, Bill Richardson — and all the rest. And Stephen Colbert may soon discover that, too.

It was hilarious when Colbert announced for president last week, and he made a big splash. He was featured on ABC News. He was given a prime spot on “Meet the Press.” Finally, we thought, somebody’s injected a little fun and humor into this dour presidential race. Kind of like Pat Paulson did back in the ’80s.

Except, unlike Pat Paulson, Colbert could make a difference. Even though he’d only be on the ballot in one state, his native South Carolina, consider this scenario: There’s only a 1,000-vote difference between Clinton and Obama, and Colbert gets 1,200 votes. He could decide the Democratic nominee.

But Colbert may never get the chance, because the FEC isn’t laughing along with the rest of us. If he’s really serious, they point out, there are two problems with his candidacy. One, he has a corporate sponsor, Doritos. Two, he has a nightly TV show. Both of which are prohibited under federal election law.

If Mitt Romney can’t be sponsored by Brylcreem, Stephen Colbert can’t be sponsored by Doritos. If Fred Thompson had to give up “Law and Order,” Colbert has to give up “The Colbert Report.”

Sorry, Monsieur Colbert. You’re a very funny guy. But running for president’s no joke.