WASHINGTON (AP) — President Barack Obama is looking for a new candidate to lead American and allied forces in Europe after his first choice, Marine Gen. John Allen, bowed out Tuesday and announced his intention to retire for what he called personal reasons.

The move further clouds the picture for Obama as he repositions key figures on his national security team and in key military leadership roles. The White House is fighting for Senate confirmation of Chuck Hagel as defense secretary; a confirmation vote was stalled last week by Republicans but is expected to happen next week.

Obama also is switching commanders at Central Command, which is responsible for U.S. military operations throughout the greater Middle East, and Africa Command.