All the praise and attention the media have spent the past four years lavishing on The Daily Show has finally gone to Jon Stewart’s head. The cover of Newsweek, on-air heart-to-hearts with Bill Moyers, a Number One New York Times bestseller, and old institutional hands like Tom Brokaw and Dan Rather groveling at his feet in every possible forum have all conspired to launch the comedian into a celebrity stratosphere where the air is so thin he forgot it was humor and impeccable comedic timing that opened the door to this particular kingdom, not his political acumen.

A sure sign of Stewart’s atrophying sense of humor was his Friday afternoon appearance on CNN’s Crossfire. Much lauded out in the hazy blips of the blogosphere, the appearance was nevertheless a boring, soulless, and, worst of all, completely humorless exercise in hubris. From the get-go it was apparent Stewart had no interest in telling jokes or even busting out any of his trademark understated cerebral mocking. He began by explaining he thought the show was “bad” and accusing the hosts of “partisan hackery,” before launching into his main self-righteous dialogue between…well, mostly between himself and his sizable ego.

“I wanted to come here today and say stop, stop, stop, stop hurting America,” Stewart admonished hosts Tucker Carlson and Paul Begala. “And come work for us, because we, as the people…need your help. Right now, you’re helping the politicians and the corporations. And we’re left out there to mow our lawns.”

When did Stewart suddenly become the established voice of “we, the people”? It looks as if the “fake news anchor” has decided to combine Ralph Nader-esque populism and vague conspiracy theories about spectral capitalism-spawned bogeymen with sarcastic humor. A registered letter from Michael Moore’s attorney cannot be far behind.

BUT, THEN, WHAT’S annoying about the newly minted Stewart the Crusader isn’t that he’s taking serious political stands. The best political comedians — Mort Sahl, Bill Hicks, Dennis Miller — have always been true believers with a core of seriousness and righteous indignation at the center of their humor. The problem with Stewart is that he demands respect but is unwilling to take responsibility for the things he says. When it is time for a Stewart lecture, there is no room for kidding around. But when his conclusions or statements are questioned, it’s suddenly time to roll his eyes and morph back into the Teflon comedian. On Crossfire, for example, after pleading with a straight face for the hosts to “stop, stop, stop hurting America” and praising his own show for its level of “civilized discourse,” Stewart summarily shot down Carlson’s questions about the kid-glove handling of John Kerry on The Daily Show last month.

“If you want to compare your show to a comedy show, you’re more than welcome to,” Stewart said, adding snarkily that he didn’t realize that, “news organizations look to Comedy Central for their cues on integrity.” When Carlson protested that he thought Stewart was going to be funny, Stewart shot back acidly, “I’m not going to be your monkey.” Blogs everywhere exploded with glee at this verbal coup de grace, but — like it or not — Carlson was making a valid point. When Stewart had John Kerry on the couch, he grilled him with questions such as, “How are you holding up? Is it hard not to take the attacks personally?” and “Have you ever flip-flopped?” Fine. No one expects Leno, Letterman, or any other late night entertainer suddenly to begin channeling Chris Matthews.

Stewart wants it both ways, however. He’ll lightheartedly lob softballs at Democrats he openly endorses for office, but when a conservative voice comes on there are few smiles and fewer mercies. In a recent post-debate interview with Rudy Giuliani, Stewart barely let the mayor finish a single sentence. Over and over it was, “But I think what John Kerry was saying was…” reducing Stewart to a pinch hitter for Mary Beth Cahill. Similarly, Ralph Reed’s views on the war in Iraq were dismissed out of hand during his visit to The Daily Show.

It’s worth noting that we didn’t hear Stewart protesting that he was just a comedian when a Kerry spokeswoman told the Washington Post, “Jon Stewart understands perfectly all the important issues facing this country right now.” In fact, in the same article, Daily Show executive producer Ben Karlin seemed to be taking the comedy show’s campaign coverage exceedingly seriously.

“All of us [on The Daily Show] are just blown away by the turn the campaign has taken,” he said. “We cannot believe that this is what is being talked about at this juncture. It’s so astounding to us. We are trying to work through our amazement and to conduct a meaningful conversation absent of incredulity.”

ABOVE ALL, THIS IS one comedy show no one is allowed to make any jokes about: When Bill O’Reilly suggested earlier this year that Stewart’s audience was made up of “stoned slackers,” Comedy Central couldn’t let such an accusation impugn the credibility of its “fake news show” and was soon feverishly issuing press releases pointing to studies that showed viewers of The Daily Show were more politically savvy and better educated than those who spend every night in the No Spin Zone. Likewise, when Carlson suggested that Stewart was “more fun” on The Daily Show, Stewart — scion of “civilized discourse” — said, “You know what’s interesting, though? You’re as big a dick on your show as you are on any show.” Umm, touché?

In the midst of this even Paul Begala’s patience, typically limitless with liberals, was tested. “Let me get this straight,” Begala said. “If the indictment is — and I have seen you say this — that… Crossfire reduces everything to left, right, black, white…Well, it’s because, see, we’re a debate show…It’s like saying The Weather Channel reduces everything to a storm front.” Earlier in the show, Stewart had demanded Begala say something nice about George W. Bush, which he graciously did. The whole thing reeked of hypocrisy. When was the last time Stewart followed his own advice? It’s a free country and any of us can say as much good or bad as we like, but don’t be a partisan jerk all the time and then lecture others on the beauty of non-partisanship. It makes you sound like Pat Leahy.

It’s all selective behavior, of course. When an interviewee with a shared viewpoint is on, it’s time to “conduct a meaningful conversation,” a “civilized discourse.” But when someone they don’t agree with is on, it’s time to raze the village. All of which is all well enough. It’s how the game is played. But when you preach your own virtues and lecture others about their deficiencies, you become a target. Maybe Bill O’Reilly and Stewart have something in common after all.