President Bush said in announcing his choice Monday, "Mike Hayden is extremely qualified for this position."
"He knows the intelligence community from the ground up."
Hayden, appearing with the president at the Oval Office announcement, said he welcomed the challenge heading the CIA would pose.
"There's probably no post more important in preserving our security and our values as people than the CIA," Hayden said.
But Hayden may face a difficult fight to win confirmation. Senate Judiciary Committee Chairman Arlen Specter, R-Pa., said before the official announcement that he would use Hayden's nomination to seek more answers about the administration's domestic spying program to gather information on suspected terrorists.
House Intelligence Committee Chairman Peter Hoekstra, R-Mich., said on CBS' "The Early Show" that he feared Hayden's nomination would detract from other important issues.
"The debate in the Senate may end up being about the terrorist surveillance program and not about the future of the CIA or the intelligence community, which is exactly where the debate needs to be," he said.
Critics on both sides of the aisle in the Senate also questioned the president for putting a military person in charge of a civilian agency.
Sen. Saxby Chambliss, R-Ga., said Hayden's military background would be a "major problem."
And Sen. Joseph Biden, D-Del., said the nomination could leave agents with the impression that the CIA has been "just gobbled up by the Defense Department," quoted the Associated Press.
However, in nominating Hayden, President Bush cited his breadth of experience. "Mike Hayden is extremely qualified for this position. ... He knows the intelligence community from the ground up."
If he receives Senate confirmation, Hayden would replace Porter Goss, who resigned under pressure Friday. Goss attempted to rebuild the agency after it came under heavy criticism for how it handled pre-9/11 intelligence and information about weapons of mass destruction in Iraq which were never found.