The Senate extended the term of FBI Director Robert Mueller for up to two years Wednesday, a day after President Obama signed legislation making an exception to the 10-year limit for an FBI chief to serve. The vote was 100-0.

Mueller was nominated to the office by former President George W. Bush and took office a week before the Sept. 11, 2001, attacks. Obama asked him to stay in office as two other major positions in his security team, the defense secretary and the CIA director, were undergoing changes.

"With the 10th anniversary of 9/11 approaching, and a continued threat from al-Qaida, we find ourselves facing unique circumstances," said Senate Judiciary Committee Chairman Pat Leahy, D-Vt. "We need leadership, stability and continuity at the FBI as the president makes necessary shifts to his national security team."

Congress had to first pass a law allowing for a one-time exception to the 10-year limit on an FBI director's term. That limit was set in 1976 as Congress reacted to the length and excesses of J. Edgar Hoover's term as FBI head. Hoover served as director from 1924 until his death in 1972.

Mueller, 66, served in the Marines in Vietnam and held positions as a public prosecutor, head of the Justice Department criminal division and U.S. attorney in San Francisco before becoming FBI director on Sept. 4, 2011. His 10-year term was to have expired next week.

Sen. Charles Grassley of Iowa, top Republican on the Judiciary Committee, said that since taking office Mueller "has overseen a top-to-bottom transformation of the FBI from a domestic law enforcement agency to a national security agency."