Washington ? Barack Obama has gone coatless in the Oval Office. His meetings sometimes run late. He opened a session with corporate CEOs with good-natured grousing about his kids’ snow days. And he gave GOP congressmen the green light to take a “whack” at him on Fox News.

Obama is launching his presidency with a laid-back style that is setting a cool-casual tone for the rest of the White House as well.

After his meeting with military commanders at the Pentagon ran late, the president apologized and admitted, “We kind of lost track of time.”

Those are words that never would have been uttered by his famously punctual predecessor. George W. Bush once ordered the door locked when Secretary of State Colin Powell didn’t make it to a Cabinet meeting on time.

The new president, a man who says he never sweats, has seemed uncowed by his new job and the majestic trappings of his new workplace.

When the White House released its first picture of the president at work in the Oval Office, there he was in his shirt sleeves.

Bush, by contrast, made it a point to be in coat-and-tie whenever he entered the Oval Office.

Obama opened a bill-signing ceremony in the East Room on Thursday with the White House equivalent of a “wassup,” casually calling out, “What’s going on?”

The night before, trying to build support for his economic stimulus package. Obama invited House and Senate leaders over to the White House for cocktails.

Cocktails? The previous president was a teetotaler.

With the economy in crisis, all ears were cocked earlier Wednesday when Obama convened a Roosevelt Room meeting with business executives.

“Can I make a comment that is unrelated to the economy very quickly?” the new president began. “And it has to do with Washington. My children’s school was canceled today. Because of, what? Some ice?”

Darrell West, director of the Brookings Institution’s governance studies program, said Obama’s tone meshes with the image he cultivated during the campaign and helps ordinary Americans identify with him.

“When you’ve campaigned as a reform-minded outsider, you need to do things differently, and the way you present yourself and interact with others tells people a lot about what you want to do,” West said. “You can always overdo it, but when three-fourths of Americans are unhappy with the status quo, almost anything you do that’s different is going to be viewed positively.”

Obama’s days tend to start and end later than his predecessor’s. Where Bush usually got his daily intelligence briefing at 6 a.m., Obama’s have started as late as 11 a.m. some days.

Where Bush was religiously early to bed, Obama’s activities have tended to stretch later into the night.

On Thursday, Obama and his wife, Michelle, ducked out briefly to catch a class presentation at 7-year-old Sasha Obama’s school.

Obama’s press secretary, Robert Gibbs, is striking a similarly casual tone.

At one briefing, he put a positive shine on the president’s meetings with congressional Republicans with this happy observation: “Nobody yelled ‘food fight.”‘

Gibbs has confessed that Obama wandered into the press secretary’s office and caught him with his feet propped up on the desk.

“I quickly put my feet down,” he said.

It was a recognition both of the informality of the Obama White House — and its limits. The days are gone when even junior campaign staffers called Obama “Barack.”