WASHINGTON, Sept. 27, 2010— -- Although no final decision has been made because of family considerations, 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.
Sources close to Emanuel cautioned that he has yet to pull that last trigger on the decision.
Emanuel's likely departure is not a surprise; his mayoral aspirations are well known.
Longtime Chicago Mayor Richard M. Daley's announcement earlier this month that he would not seek reelection created the opportunity that Emanuel has long been seeking.
The former Chicagoan has never been coy about his desire to head the proverbial City With Shoulders.
"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 Daley's announced exit, ambitious Chicago Democrats quickly began angling to replace him, creating pressure for Emanuel to make a decision on his White House position soon, even coming from the president himself.
"I think that Rahm will have to make a decision quickly, because running for mayor of Chicago is a serious enterprise," President Obama said Monday on NBC's "Today Show." "He hasn't told me yet. But as soon as he does, I'm sure that we'll announce it."
The president has been clear that Emanuel has his blessing when the job opened, aides calling it an "unbelievably attractive opportunity" for anyone that the president would support.