WASHINGTON – Defense Secretary Donald Rumsfeld resigned Wednesday within hours of a stunning Republican setback in nationwide midterm elections, a vote that became a referendum on President Bush’s strategy for the war in Iraq and on Rumsfeld’s stormy stewardship of the Pentagon.

Bush announced Rumsfeld’s departure during a press conference, stating that he had nominated former CIA Director Robert Gates as his next secretary of defense. All three men convened later in the Oval Office of the White House to discuss the changing of the guard.

While Bush explained his decision as a need to put “fresh eyes” on his Iraq policy, it came after voters Tuesday turned over control of the House to Democrats, who had made the military stalemate in Iraq a campaign priority. The Senate may fall to Democratic hands as well, pending the outcome of a close race in Virginia.

Rumsfeld’s sudden departure was the clearest signal yet that Bush may soon make a dramatic shift in his Iraq war strategy.

Rumsfeld, the Pentagon chief since Bush took office in January 2001, was viewed as the key architect of the 2003 military invasion of Iraq, and in more recent times the public face of the failures there. His ouster could both embolden the military, with which he was often at odds, and those who have pressed for solutions that Rumsfeld strongly opposed, such as a partitioning of Iraq.

Rumsfeld’s primary strategy of having U.S. troops train Iraqi military and police units to take over security in Iraq was viewed by critics as progressing slowly and poorly managed. There were also complaints about the soaring cost of reconstructing Iraq’s neglected infrastructure, overcharges by private Pentagon contractors and a perceived lack of adequate U.S. troop strength.

During his press conference, Bush seemed almost eager to meet with a congressionally mandated group of experts who are soon to make recommendations on options for the U.S. forces in Iraq; the president said that session will occur next week. That panel, known as the Iraqi Study Group, is co-chaired by James Baker, a Bush family friend who served as secretary of state during Bush’s father’s presidency, and former Indiana Democratic congressman Lee Hamilton.

The speed of Rumsfeld’s resignation caught official Washington by surprise. A combative bureaucrat with a razor-sharp wit, Rumsfeld was expected by many to depart only when conditions in Iraq improved. Bush only last week offered assurances that Rumsfeld would stay, and that Rumsfeld and Vice President Dick Cheney, another enthusiastic proponent of the Iraq war, were doing a “fantastic job.”

Rumsfeld’s combative nature made him a soft target for those who oppose the war in Iraq, and for Democrats and some Republicans in Congress who came to question the Bush administration’s assessment of the U.S. military mission there.

Rumsfeld offered to resign twice before, both times during the scandal that erupted in April 2004 over the abuse of Iraqi prisoners by U.S. soldiers. Bush then refused to accept Rumsfeld’s offers to quit.