President Barack Obama, seen here with wife Michelle and daughter Sasha vacationing in 2010, wants to be able to look his children in the eye and deny it should they ever ask him whether he smokes. his wife says. ((Susan Walsh/Associated Press)) President Barack Obama finally has kicked the habit, Michelle Obama said Tuesday.

"Yes, he has," the first lady told reporters at the White House when asked whether her husband had finally done what millions of Americans can't seem to do and quit smoking. "It's been almost a year."

She offered no details on when he quit or, more importantly, how he quit, "because he never smoked a lot," and she never saw him light up.

Obama is known to have chewed nicotine gum to help. After his first medical checkup as president last year, the White House physician said in a statement issued after the exam that Obama should stick with "smoking cessation efforts" — the use of nicotine gum.

One in five adults in the U.S., or 46 million people, still smoke, and tens of millions more are regularly exposed to secondhand smoke.

Although the smoking rate in the U.S. has dropped dramatically since 1964, when the first surgeon general's report declared tobacco deadly, progress has stalled in the past decade.

The government had hoped to drop the smoking rate to 12 per cent by last year, a goal not only missed but now pushed to 2020.

More direct

The issue of Obama's smoking last surfaced in December, when press secretary Robert Gibbs was asked about it and said he hadn't seen Obama smoke in nine months. That would have put Obama's final puffs sometime in March.

At the time, Gibbs stopped short of asserting that the president had quit outright, but the president's wife was a bit more direct Tuesday.

"He's always wanted to stop," the first lady said, explaining that daughters Malia, 12, and Sasha, 9, are getting to an age where he wants to be able to look them in the eye and deny it should they ever ask him whether he smokes.

Mrs. Obama said the process of quitting has been a "personal challenge" for the president who, when questioned about it in June 2009, acknowledged that he often sneaked an occasional puff.

"I constantly struggle with it," Obama said. "Have I fallen off the wagon sometimes? Yes. Am I a daily smoker, a constant smoker? No."

Obama said he didn't smoke in front of his kids or his family, and had declared himself "95 per cent cured." But he acknowledged then that there still were times "where I mess up."

"Once you've gone down this path, then it's something you continually struggle with," he said.

Don't mess with them

Mrs. Obama said Tuesday that she was proud of her husband, but hasn't pressed him for details.

"I haven't really poked and prodded him on this," she said.

"When somebody's doing the right thing you don't mess with them."

Brain research shows nicotine is powerfully addicting. In surveys, 70 per cent of smokers say they want to quit, but only about 40 per cent try in any given year.

The U.S. National Institute on Drug Abuse says three-quarters who try relapse within six months. It usually takes repeated attempts to completely quit long-term. NIDA cites research that shows extended smoking cessation care can help half of quitters stay cigarette-free at one year.

Gibbs said Tuesday that a few White House aides had also quit smoking, including trip director Marvin Nicholson.

"When somebody decides to quit smoking, to try to overcome the physical addiction that they have, they do it not just because they want to but because others want them to, and because others around them give them the type of encouragement that they need to break what is a tough habit to break," Gibbs said during his regular media briefing after being told of the first lady's comment.