Obama, D-Ill., resolved to quit his cigarette habit over the winter holidays, just weeks before his expected presidential campaign would make photographers and reporters an even more regular part of his life.

He said in an interview yesterday that, although he has never been a heavy smoker, he has quit for periods over the last several years but then slipped back into the habit. On the cusp of a potential presidential bid seemed the right time to quit for good, he said.

"I've never been a heavy smoker," Obama said. "I've quit periodically over the last several years. I've got an ironclad demand from my wife that in the stresses of the campaign I don't succumb. I've been chewing Nicorette strenuously."

The incentive to quit is great for any office seeker, as increasingly negative attitudes about smoking translate into political pressure not to do it — or at least not to be caught doing it publicly. At a time when most willing public figures also are expected to serve as role models, those with unhealthy habits face intense pressure to leave them behind.

Americans haven't elected an open and unabashed cigarette smoking president since Franklin D. Roosevelt, though others such as Lyndon Johnson smoked on occasion. The rules seem also to extend to political spouses such as first lady Laura Bush, who found it necessary to quash her habit, or at least take it underground.

In Obama's case, the pressure isn't just political. His wife has always been concerned about his smoking and, over the holidays, according to family friend Valerie Jarrett, the two of them agreed that he "should stop now."

"He began the process of quitting over Christmas," Jarrett said. "I have not heard of him smoking over the last several weeks."

There's a little hedge room in the time frame, allowing for the possibility that Obama's resolve might have slipped a time or two. Obama didn't clarify the point.

Kicking the habit is good for just about any politician's image, said Irving Rein, a Northwestern University communications studies professor and author of "High Visibility," which examines the marketing of celebrities. Attitudes toward smokers have changed dramatically since FDR's triumphal display of his ivory cigarette holder in an era when smoking made a person seem elegant and powerful.

Back then, Hollywood glamorized cigarettes almost as fashion accessories. Attitudes had radically changed by the late 1990s, when first lady Hillary Rodham Clinton criticized actress Julia Roberts for portraying a movie character with a compulsive smoking habit.

For Obama, it's an especially smart play to grind out his last cigarette, Rein said.

"Brand has become so big with personalities. It includes the kind of suit he wears and the shoes he chooses," said Rein. "Smoking is part of that package. It doesn't go with the social, environmental message of reform he would like to project. His image would be impacted by it."

Regardless of whether his image has suffered, his lungs most likely have. Longtime friends say Obama was a smoker when he was in his first two years of college at Occidental College in California, from 1979 to 1981.

He said yesterday that he has never smoked more than 10 cigarettes a day, and usually only four or five. He said the number usually went up when he was either writing or campaigning.

He said he isn't using the patch because he worries that they're too strong for him.

"I'm not somebody who's all that hooked," he said. "I didn't want more nicotine coming to me than I had been ingesting."

While quitting during such a stressful period as a presidential campaign may be difficult, public health advocates count it as a victory for them.

"I hope he makes it a public fight," said Mark Peysakhovich of the American Heart Association, who used to lobby Obama on anti-smoking policies and other public health issues when Obama was a member of the Illinois Senate. "If he's got a nic fit and he's in a bad mood, I hope some of that comes out. Maybe it will encourage other people to be brave enough to try."

It might even score some political points for Obama, he said.