Like the beat beat beat of the tom-tom, like the tick tick tock of the clock, like the drip drip drip of the raindrops, a voice within me keeps repeating, Obama Obama Obama.

With all due apologies to the author, Cole Porter's lyrics of "Night and Day" make a point lost on the president. No matter where he is, the Oval Office or Jay Leno's studio set, addressing Congress or holding up traffic in a motorcade on his way to a PTA meeting, the president is not an ordinary citizen. Like it or not, those days are behind him. The private man and the public man become as one in a president. What he does, says, or doesn't say or doesn't do, he does it before an audience.

Obama goes out of his way to seek a celebrity's attention, and he's still in his first hundred days. When he makes an off-hand jest about his bowling score and the Special Olympics -- the sort of tasteless attempt at dark humor that anyone might make within a tight circle of good friends -- the whole world hears it, and the pundits can't wait to leap. We should all "lighten up," but if a president can't resist going on television to banter with a comedian, he ought to leave the comedy to the comedian, who gets paid for sarcasm and irony.

It's a shame that the eye of the camera tempts presidents to try to be the entertainer in chief. Michelle might emulate Bess Truman after Harry couldn't resist playing the piano with Lauren Bacall in fetching repose atop the upright. Mr. Truman, on a night out at the National Press Club, was only doing what any red-blooded man might, but Bess was not amused. She told him it simply wasn't dignified, that he was definitely not to "play it again, Harry."

Dignity, of course, isn't what it used to be. Indeed, the concept seems faintly quaint in an era when almost anything goes. As comfortable as the president may look on the CBS show "60 Minutes," with Jay Leno or in a primetime press conference, he's spending valuable emotional and intellectual capital with the relentless exposure in the modern media. Confident and cool, he's nevertheless beginning to look a lot like a man afflicted with the hubris of show biz.

Since the campaign ended, the stakes have changed. He has yet to understand the lesson learned by Steven Chu, his secretary of energy. Asked what he likes least about his new job, he replied: "The fact that I'm constantly being told that I have to be careful what I say to the press and in public. I can't speculate out loud anymore. Everything I say is taken with total seriousness."

Even laughter can be suspect. Steve Croft, the president's interviewer on "60 Minutes," suggested the president might be "punch drunk" when he chuckled aloud in discussing the crash of the economy. "Gallows humor," the president later called it. But that doesn't work for a president, whether hot or cool. Most of us didn't expect Bill Clinton to feel our pain, and we don't expect Barack Obama to laugh at it.

None of this will matter much if, as he suggested it would in his press conference this week, the economic crisis soon eases. He'll get the credit, and that's how it should be. But there should be a bright line between behaving as the commander in chief and entertaining as a celebrity in chief.

The history of Washington and Hollywood eager to trade places is a long one. Politicians and entertainers imagine themselves as stars in the same galaxy. Bette Davis and Humphrey Bogart campaigned for FDR, to the dismay of studio executives (that, too, seems quaint today). JFK enjoyed the company of Marilyn Monroe and was pals with Frank Sinatra (who later liked to hang out with the Reagans). Barbra Streisand sometimes slept at the White House (in the Lincoln Bedroom, of course) during the Clinton years.

Said Gerald Ford, in another context, "If Lincoln were alive today, he'd be spinning in his grave." Lauren Bacall understood the "natural attraction" between Washington and Hollywood. "They have access to real power, and we sing, dance and act."

The modern president crosses that bright line between statecraft and stagecraft at his peril. Obama would do well to remember that statecraft is what we elected him to manage. He should leave the barbs and yuks to the professionals.