WASHINGTON--President Obama announced Rahm Emanuel's departure from his White House job on Friday--Emanuel starts a run for Chicago mayor Monday--in a jammed East Room event marked by sentiment and emotion. Both Emanuel and Obama said Emanuel's leaving is "bittersweet."

Emanuel leaving the White House on Friday was well known by the time it happened---and Obama joked about it at the top of his remarks.

"Good morning, everybody, and welcome to the least suspenseful announcement of all time. As almost all of you have reported -- my chief of staff, Rahm Emanuel, has informed me that he will be leaving his post today to explore other opportunities. This is a -- a -- a bittersweet day here at the White House," said Obama in a room filled with at least ten members of the cabinet, top staff and Emanuel's family.

"On the one hand, we are all very excited for Rahm as he takes on a new challenge for which he is extraordinarily well-qualified. But we're also losing a(n) incomparable leader of our staff, and one who we are going to miss very much."