The most senior woman ever appointed to a military job is leaving the Pentagon. Michele Flournoy, undersecretary of defense for policy, announced today that she was leaving to “rebalance” her life. It has been an extremely busy life for the woman occupying what is generally regarded as the Pentagon’s number three position. On top of the three years she has served her country while it waged two wars, Flournoy’s husband has been one of the top officials in the Veterans Administration.

But there may be another reason — a very Washington reason — for Flournoy’s departure, some speculate. She was a keen supporter of the Obama campaign from very early on and having a committed supporter, a senior woman with three years serving at the highest levels of the Pentagon may be a good thing for the Obama campaign this time.

“From a campaign point of view she is a very valuable commodity,” said a longtime observer of Capitol Hill and the Pentagon. “A high-ranking woman in national security: how many of them are there in either party?” She would not, this source speculated, be the first official to step out for a breather a year before an administration’s end only to grab a a plum assignment should the president get reelected.

Flournoy’s departure plan was clearly mapped out for her. There was the interview with the Associated Press to quickly and efficiently deliver the news to the rest of the media. Defense Secretary Leon Panetta issued a kind statement soon after the interview appeared.

“In her discussions with me, Michèle made clear that her decision to leave is motivated by personal and family considerations. I am very pleased that she has agreed to stay on until early next year to enable a smooth transition,” Panetta said. “From guiding our strategy in Afghanistan and Iraq, to helping set the department’s priorities and global posture through the 2010 Quadrennial Defense Review as well as the strategy review that has been underway this year, Michèle has made a strong and lasting positive imprint on this department and on our nation’s security.”

Flournoy has also left a well-entrenched team of proteges in the senior reaches of the Pentagon. Between the many acolytes who marched from the Pennsylvania Avenue offices of the Center for a New American Security — which she co-founded — and the many highly qualified women she helped find places in the Pentagon, she has an army of like-minded people who can keep her informed about what is really happening in the big building across the river.

Then again, having known her moderately well for some time, it’s just as likely she’ll rest on her laurels for a bit, sleep a lot for a while and then resume the influential role of serving her country in relative quiet as one of America’s most respected strategic and military thinkers. Then again, many of them may be as ready as Flournoy to take a breather. She may be just the first of many senior officials heading for the Pentagon’s doors.