Gen. Michael V. Hayden (AP Photo/Lauren Victoria Burke)

At a White House news conference, Bush said Michael Hayden was "the right man to lead the CIA at this critical moment in our nation's history."

In August 2004, Bush said of his then choice of Porter Goss as CIA boss: "He's the right man to lead this important agency at this critical moment in our nation's history." With Goss at the helm, the CIA suffered one of its biggest talent drains ever, as dozens of long-time staff members left the agency, uncomfortable with his leadership.

Hayden's most recent job was deputy national intelligence director. Between 1999 and 2005, he was the director of the National Security Agency. Within weeks of the Sept. 11, 2001, terrorist attacks, Hayden authorized a secret eavesdropping program in the "war on terrorism." Under the controversial program, the agency ordered electronic surveillance – without court orders – of international phone calls and e-mails of people in the United States, when terrorism was suspected.

Bush has vigorously defended the program, despite widespread public – and political – criticism of it. Republican Senator Arlen Specter has said he would use Hayden's appointment to raise questions about the legality of the wiretap program.

Shortly after the New York Times exposed the program's existence in December 2005, Hayden fiercely defended it in a speech to the National Press Club.

"These are communications that we have reason to believe are al-Qaeda communications, a judgment made by American intelligence professionals, not folks like me or political appointees," he said.

"So let me make this clear. When you're talking to your daughter at state college, this program cannot intercept your conversations. And when she takes a semester abroad to complete her Arabic studies, this program will not intercept your communications."

It's no surprise that Democrats would take issue with Hayden's appointment. They've cited his involvement in the wiretap program as well as the fact that he's an active four-star general. As well, several Republicans have said Hayden's military background is "troublesome." The CIA is a civilian – rather than a military – agency.

Dianne Feinstein – a Democratic senator from California – urged Hayden to retire from the military, to take care of that issue.

Stansfield Turner – who led the CIA under the administration of President Jimmy Carter – said he had no problem with a member of the military at the helm of the CIA. Turner was an admiral when he had the job.

But Turner did express concern over the wiretap program.

"I think it's bad for the country to have the chief of intelligence having telephones in the United States monitored without somebody else approving it."

Hayden grew up in a blue-collar neighbourhood of Pittsburgh. His father worked at a manufacturing company. Hayden held a part-time job as a cab driver while earning bachelor's and master's degrees in history at Duquesne University. He received his commission as an officer in 1969, while in university, under the Reserve Officer Training Corps.

Hayden was promoted to the rank of major in 1980. On April 22, 2005, he was named a four-star general. Between 1991 and 1993, he was chief, Secretary of the Air Force Staff Group at air force headquarters in Washington. In 1993, he moved to Stuttgart, Germany, to take on the role of director, Intelligence Directorate at the U.S. European Command.

Hayden is said to be an ardent fan of both the Pittsburgh Steelers and William Shakespeare.