WASHINGTON -- The Senate on Tuesday unanimously approved the nomination of Leon Panetta to be the next Pentagon chief, handing him a crowded agenda of overseeing the drawdown of U.S. troops in Iraq and Afghanistan, tamping down congressional unrest over the Libyan conflict and cutting the budget.

Panetta will replace Defense Secretary Robert Gates, who is retiring June 30 after 4 1/2 years on the job through the administrations of Republican George W. Bush and Democrat Barack Obama.

Panetta, the CIA director during the successful operation to kill terrorist leader Osama bin Laden, received strong bipartisan praise as well as a 100-0 vote.

"Just a home-run choice. The president made a very wise decision," said Sen. Lindsey Graham, R-S.C.

Panetta, 72, a former congressman, chairman of the House Budget Committee, one-time director of the Office of Management and Budget and Bill Clinton's White House chief of staff, faces several high-stakes assignments, starting with Obama's initial withdrawal of U.S. forces from Afghanistan this summer.

American troops also are slated to leave Iraq by year's end. And Gates has indicated that he's likely to certify that gays can serve openly in the military, implementing the new policy.

Obama has called for some $400 billion in cuts over the next 12 years amid intense budget pressures, a certain test of Panetta's skills.

"He is the most qualified individual to tackle the huge budgetary issues," said Sen. Jack Reed, D-R.I.

Senate Armed Services Committee Chairman Carl Levin, D-Mich., said the defense budget should not be exempt from cuts. The Pentagon chief, Levin said, will need to look at every military program and expense and "make the tough choices and trade-offs between our warfighters' requirements today and preparations for the threats of tomorrow."

Said Senate Majority Leader Harry Reid, D-Nev.: "In this time of tight budgets, he knows how to do more with less."

Panetta also faces frustrated lawmakers, upset with Obama's decision not to get congressional consent for the 3-month-old military operation against Libya. Several lawmakers in the House are pushing to cut off funds for the mission.