The Q&A at an architecture convention in Orlando came days after her husband made his first public comments as ex-president at a Chicago university.

Mrs Obama, who left office with a 68% approval rating (10% more than her husband) said "politics is tough."

"It's all well and good until you start running, and then the knives come out."

It's hard on a family, she said. "I wouldn't ask my children to do this again because when you run for higher office, it's not just you. It's your whole family."

But "public service will always be in our blood", she added.

Although Mrs Obama had played down her political ambitions before, while first lady, this is the first time she has done so since the election campaign, when she was widely viewed as the most effective weapon in the Democratic armoury.