Michelle Obama on Keeping Family Life, Politics Separate: 'I Rarely Step in the West Wing'

Oct. 8, 2012— -- First lady Michelle Obama is campaigner-in-chief when it comes to stumping for her husband and a key asset on the trail, yet she rarely talks about the inner workings of her marriage.

"Nightline" was granted wide-ranging access to Mrs. Obama, who opened up about adjusting to life in the White House, but said she no longer has any doubts that they are doing what's best for their family and the country, and is looking forward to another four years.

Mrs. Obama is the president's biggest supporter and often his most honest critic. But she admits, there are times when it's best to temper her responses.

"In a job like this, the last thing the president of the United States needs when he walks in the door to come home is someone drilling him and questioning him about the decisions and choices that he's made," Mrs. Obama told "Nightline" anchor Cynthia McFadden in an interview at the White House. "There are definitely times when I may feel something, but I'll hold back because I know he'll either get to that on his own or it's just not time."

The first lady was adamant that she steers clear of influencing her husband's policy, opting instead to champion her own issues, such as the fight against childhood obesity and her work with military families.

"I rarely step foot in the West Wing. In fact people are shocked when they see me there," she said. "I rarely walk in that office because the truth is he's got so many wonderful advisers. He's got a phenomenal cabinet. He's got people who are in the trenches on these issues every single day and I'm kind of stepping in and out and I've got my own set of issues. So I don't even have the kind of expertise and the time in to be able to provide the kind of advice and guidance that he's already getting."

The first lady has acknowledged that she was reluctant to raise their two daughters in the White House, but four years later, she is confident they are doing what's best for their family, and the country.

Part of their success has been finding a way to preserve family time. "One of the things that Barack and I try to do in our lives which I think is one of the reasons our family is so whole, is that we make sure family is family -- it's not this sort of quasi-business relationship. We really do -- we're two people who love each other and put a lot of our energy into our kids and into our family unit," she said.

But the first lady was not always on board. Her brother Craig Robinson recently told ABC News that then-Senator Obama recruited him to help convince his sister that a run for the White House was the right move.

"He said to me 'you've got to do me a favor,'" Robinson explained. "'You've got to talk to her because she is not gonna go for it.' I said 'you're right. You're darn right she's not gonna go for it.'"

"I eventually talked to her, and I said to Michelle you know, I said you cannot penalize Barack for being good at what he does," he said.

Ultimately, Mrs. Obama said she felt she had to acquiesce.

"In the end, Barack, our family is priority for him, and I knew that if I said no he wouldn't do this," she said. "And then I had to think of whether I would want to be responsible for not having somebody like Barack you know, someone with his level of intellect, his honesty, his compassion, his vision. Would I want to be the one who stood in the way of this person potentially running this country? And I couldn't do that, because then I had to think beyond myself and my family and I had to think of sort of the broader benefits that this country could gain from his leadership."