Exit Rahm Emanuel, Enter Pete Rouse

It's the worst kept secret in Washington. But White House sources are now confirming that Chief of Staff Rahm Emanuel will indeed take off to run for mayor of Chicago. He will be replaced by Pete Rouse, currently serving as a senior adviser to President Obama. The president is expected to officially announce the change on Friday. It's not clear whether Rouse will take the job on a permanent basis or just until the midterm elections.

For the famously abrasive Emanuel, the move caps a tumultuous 18 months ramrodding Obama's agenda through an unruly, Democratic-controlled Congress. It's a remarkable getaway from the nation's capital for someone who once dreamed of becoming the first Jewish speaker of the House of Representatives. Still, running Chicago is one of the country's plum political jobs and Emanuel always indicated that if his mentor, Mayor Richard M. Daley, retired, he would go for it. Chicago being Chicago, the election is no sure shot and Emanuel will soon be re-acquainting himself with its seamy stew of racial politics.

As for Rouse, the low-key aide is widely respected in Washington. He has previous experience running Obama's office during his freshman term as a senator from 2004, and before that, the office of Tom Daschle, then Senate majority leader. "The type of trust the president and others in the administration have in Pete is enormous," said White House press secretary Robert Gibbs.

With Democrats expecting heavy losses in November, guiding Obama's legislative priorities through Congress is only likely to become trickier. The new chief of staff will be required to link arms as well as twist them. For the administration, it's never ideal for a leading light to head for the exit. And who knows? If a Democratic bloodbath ensues on Nov. 2, calls may grow louder for a "wise elder" to come in and steady the ship - someone like Clinton holdover Erskine Bowles, experienced at working with a GOP-controlled Congress.

In the meantime, Rouse will have to fit the bill. In comes the diplomat, out goes the brawler.