Report: Rahm Emanuel 'Likely' to Step Down This Week

No official announcement has come from the White House yet, but speculation is buzzing around Washington that chief of staff Rahm Emanuel will be leaving his post at the White House this week:

ABC News has learned that White House officials are preparing for Chief of Staff Rahm Emanuel to announce on Friday -- as Congress adjourns for recess -- that he is leaving his post to explore a run for mayor of Chicago.

White House officials expect that President Obama will also name an interim chief of staff, perhaps senior adviser Pete Rouse, at the announcement.

The announcement is no surprise given that Emanuel has been eager to run for the Chicago mayor's office.  "One day I would like to run for mayor of the city of Chicago. ... That's always been an aspiration of mine, even when I was in the House of Representatives," Emanuel said in April to Bloomberg's Charlie Rose.

With current Mayor Richard Daley retiring at the end of his term, Emanuel is the likely front-runner for the Democratic nomination.