Now he is starting the cycle again: he is scheduled to appear on “This Week With George Stephanopoulos” on Sunday morning. Even writing this column shows how I’ve become part of his joke, which is expanding into the media landscape the way the Blob attacked a small town.

This all makes you realize something that has been a longtime thematic undercurrent of “The Colbert Report”: Mr. Colbert is a serious performer playing a silly character, while the media and political world are deeply silly but pretending to be serious. That was never more clearly illustrated than in the most triumphant part of his show on Thursday, when the respected Politico writer Mike Allen offered a (mock?) serious analysis of his prospects, citing polls and strategy. With little prompting, he started game-planning the nonexistent and probably never existent campaign, becoming part of the joke as well. The journalist Joshua Green played a similar cameo role last election.

You’ve heard of fantasy baseball? This is fantasy politics. And it’s perfectly suited to a cycle in which journalists spent weeks obsessing over the political future of the host of “The Apprentice.” Incidentally, one of the funniest moments in the current campaign occurred when Rick Santorum told Politico that he would not draft a player on his fantasy baseball team who is a known steroid user. (I want to be in his league!)

The most remarkable thing about prominent political journalists speculating about a fake candidate is that it seems so normal now. What makes Mr. Colbert such an ingenious satirist is not just that he exposes political fantasy but that he also takes it to its illogical conclusion. After all, the first issue ad that he made with “funds” from his super PAC starred a theoretically real candidate, Buddy Roemer, standing on a fake set with fake books, and ended with Mr. Colbert on a unicorn proclaiming, “To Narnia!”