WATCH LIVE: Obama speaks at farewell tribute for Defense Secretary Panetta

Panetta is leaving the administration after stints as CIA director and secretary of Defense. 

While today isn't his last day in office, Panetta will depart his post when the Senate confirms his successor. 

The president's chosen replacement, former Sen. Chuck Hagel (R-Neb.), endured tough questioning and delivered an uneven performance at his confirmation hearing last week.

Panetta defended Hagel on NBC"s "Meet the Press" this past weekend, saying that the senators spent too much time questioning Hagel about past quotes instead of issues that the secretary of Defense confronts today.

“What about the war … in Afghanistan? What about the war on terrorism? What about the budget sequestering, what -- what impact it's gonna have on readiness?” Panetta asked.

Hagel is expected to win confirmation despite his missteps given the Democratic majority in the Senate.

In what could be Panetta's last public congressional hearing, the secretary of Defense testified on Thursday before the Senate Armed Services Committee on the attack in Benghazi, Libya.

Testifying alongside Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey, Panetta defended the Pentagon's response to the Sept. 11 attacks that left Ambassador Christopher Stevens and three other Americans dead.

“Without adequate warning, there was not enough time, given the speed of the attack, for armed military assets to respond,” Panetta told the panel.