President Bush's sudden selection of former CIA Director Robert Gates as defense secretary brings back a member of the team that waged the successful first Gulf War with just two years to resuscitate the faltering U.S. policy in Iraq.

Explaining his decision on Wednesday, Bush portrayed Gates as a force of change and a solid leader who will make the necessary adjustments in Iraq — and elsewhere.

"He understands we're in a global war against these terrorists. He understands that defeat is not an option in Iraq," Bush said. "And I believe it's important that there be a fresh perspective."

Gates' resume as a government policymaker is not untarnished. Critics dredged up his 1991 confirmation hearings to be CIA director as evidence he is the wrong man for the job. Then, he was criticized for missing clues about the impending fall of the Soviet Union and for politicizing Cold War intelligence. Those two complaints — misreading intelligence and using it selectively — have also dogged the Bush administration in its Iraq policy.

But supporters see Gates as a seasoned policymaker who climbed the CIA bureaucracy from an entry-level position to become director under the elder President Bush. He also served on his National Security Council, as he had for Presidents Carter and Reagan.

Bush noted that Gates helped lead U.S. efforts to drive the Soviets out of Afghanistan in the 1980s while at the CIA and was deputy national security adviser during Operation Desert Storm.

Now, he is part of the Iraq Study Group, a bipartisan panel led by former Secretary of State James Baker III and former Rep. Lee Hamilton, that has been asked to help chart a new course in the war-ravaged nation.

George Edwards, a political science professor at Texas A&M University, where Gates is president, said Rumsfeld's departure is a rejection of the neoconservative policies that have dominated the Bush administration. He sees Gates as stylistically different from Rumsfeld: less combative, more civil and someone who won't follow the rigid neoconservative line.

In Gates, he said, Bush chose an agent for change.

"The president has got a very great challenge" in Iraq, said Edwards, whose expertise is the U.S. presidency. "There is no silver bullet. We are going to be there for a while no matter what, and his legacy rests very heavily on what happens."

Rumsfeld, 74, has served in the job longer than anyone except Robert McNamara, who became secretary of defense during the Kennedy administration and remained until 1968. Rumsfeld is the only person to have served in the job twice; his previous tour was during the Ford administration.

He was at the Pentagon and personally helped in rescue efforts after suicide hijackers crashed a plane into the building on Sept. 11, 2001. He then oversaw the U.S.-led invasions of Afghanistan and Iraq.

The White House hopes that replacing Rumsfeld with Gates can help refresh U.S. policy on the deeply unpopular war and perhaps establish a stronger rapport with the new Congress, where Rumsfeld had strained relations.

Rumsfeld said it was a good time for him to leave. "It will be a different Congress, a different environment, moving toward a presidential election and a lot of partisanship, and it struck me that this would be a good thing for everybody," he said.

Speaking at Kansas State University on Thursday, a nostalgic Rumsfeld called his service as defense secretary "the highest honor" of his life and said the United States is "engaged in a new and unfamiliar war that is, even today, not yet well understood."

Like Rumsfeld, Gates has served in the federal government for decades.

A native of Kansas, he joined the CIA in 1966. By 1987, he became acting CIA director, when William Casey was terminally ill with cancer.

Questions were raised about Gates' knowledge of the Iran-Contra arms and money affair, and he withdrew from consideration to take over the CIA permanently. Yet he stayed on as deputy director.

Then-national security adviser Brent Scowcroft, who has been a critic of the younger Bush's policies, asked Gates to be his deputy in 1989 during the administration of Bush's father. The elder President Bush asked Gates to run the CIA two years later.

Gates won confirmation, but only after hearings in which he was accused by CIA officials of manipulating intelligence as a senior analyst in the 1980s.

Melvin Goodman, a former CIA division chief for Soviet affairs, testified that Gates politicized the intelligence on Iran, Nicaragua, Afghanistan and the Soviet Union. "Gates' role in this activity was to corrupt the process and the ethics of intelligence on all of these issues," Goodman said.

The Bush administration's use of intelligence on Iraq has been a central theme of criticism from Democrats who say the White House stretched faulty intelligence from U.S. spy agencies to justify invading Iraq in 2003.

Rep. Rush Holt, D-N.J., a member of the House Intelligence Committee, called Gates' selection troubling, given that history. "What we need going forward in Iraq is straight talk about the challenges we face," he said.

Yet John Hamre, a former deputy secretary of defense during the Clinton administration and member of the Iraq Study Group with Gates, predicted a smooth confirmation process. "He will get very strong support on both sides of the aisle," Hamre said. "He's intellectually honest and fair."

Gates has taken a much lower profile since leaving the CIA and the government in 1993. He joined corporate boards and wrote a memoir published 10 years ago, "From The Shadows: The Ultimate Insider's Story of Five Presidents and How They Won the Cold War."

Gates is a close friend of the Bush family. He was interim dean of the George Bush School of Government and Public Service at Texas A&M and became the university's president in 2002. The school is home to the elder Bush's presidential library.

The current president met Gates on Sunday at his Texas ranch and said he found they were of like minds. He said the Republican defeats in Tuesday's elections didn't affect his decision to replace Rumsfeld.

"Win or lose, Bob Gates was going to become the nominee," Bush said.