President Bush announced the resignation of U.S. Secretary of Defense Donald Rumsfeld Wednesday, one day after Republicans suffered a significant defeat in Congressional elections.
At the White House, Mr. Bush said he and Rumsfeld had a "series of thoughtful conversations" and agreed the "timing is right" for new leadership at the Pentagon.
He said he is nominating former CIA chief Robert Gates to succeed Rumsfeld.
Mr. Bush acknowledged that Iraq played prominently in the U.S. congressional elections, but indicated the election results were not a factor in Rumsfeld's resignation. The president said that -- "win or lose" -- Gates was going to be nominated.
Later with Mr. Bush at the White House, Gates said the United States faces serious challenges to peace and security, and because of those risks, he said he did not hesitate when asked to return to public service.
Rumsfeld said he looks forward to working with Gates in the transition and said it has been the highest honor of his life to serve as secretary of defense.
A Pentagon spokesman, Bryan Whitman said the details of the transition would be worked out in the coming days.
The Gates appointment must be approved by the Senate.
Rumsfeld has served nearly six years as secretary of defense under Mr. Bush.
Gates is currently the president of Texas A&M University in College Station, Texas. He has held that post since 2002.
Before moving to academia, he spent almost three decades working in intelligence. In 1966, he joined the CIA as an entry-level employee and eventually worked his way up to the top post of director, which he held from 1991 to 1993.
Gates has served under six presidents in both parties, including Mr. Bush's father, former President George H.W. Bush.