Rumsfeld, President Bush's sole defense secretary in six years of leadership, is the first administration casualty after a midterm congressional election that sent at least 28 House Republicans packing and left the future of the Senate in limbo.
President Bush called Rumsfeld a trusted friend and patriot who had served his country well.
"Now after a series of thoughtful conversations, Secretary Rumsfeld and I agreed that the time had come for new leadership at the Pentagon," Bush said in an East Room press conference scheduled Tuesday night after election returns showed an incoming Democratic House majority.
"Don Rumsfeld has been a superb leader during a time of change. Yet he also appreciates the value of bringing in a fresh perspective during a critical period in this war," he said.
Rumsfeld's departures was a surprise to many after his office gave no indication earlier in the day that the congressional outcome would impact his decision. Just last week, Bush said he had full faith in Rumsfeld. Then again, he acknowledged Wednesday that he thought Republicans would retain the House.
