The Senate on Friday unanimously approved Lt. Gen. David Petraeus to become the new U.S. forces commander in Iraq, less than a month after President Bush outlined a new strategy in the war-torn country that is facing opposition in the Democrat-led Congress.

Petraeus replaces Gen. George Casey, who has been nominated to be the next Army Chief of Staff.

The Senate approved Petraeus' nomination in an 81-0 vote.

Sen. John Warner, R-Va., a former secretary of the Navy who recently has become critical of the president's war planning offered advice to Petraeus before he cast his vote.

"On the battlefield, decisions must be made in a matter of seconds, from the platoon level up the chain of command. We cannot have finger-pointing. We cannot have a mission where an Iraqi lieutenant said we should go left, the American embedded officer or whomever commands the Americans in that situation, says go right, [and] the mission not achieve its goal. ... It's going to be extremely complex," Warner said.

Friday's vote followed a unanimous recommendation Wednesday from the Senate Armed Services Committee on Wednesday approved Petraeus' nomination, and approval looked locked down before the vote took place.

"I think we will confirm him," Sen. Richard Shelby, R-Ala., told FOX News on Friday.

In taking the top military post in Iraq, Petraeus also would be promoted to a full-general, with four stars on his shoulder boards.

Bush named Petraeus to replace Casey as part of a revamping of his top military and diplomatic officials in Iraq and the Middle East. The president has proposed sending another 21,500 troops to Iraq to help stabilize the country, but the new Congress is considering two non-binding resolutions that would rebuke the president's war plans. Neither of the leading proposals, however, has the force of law.

Before the nomination vote Petraeus was meeting with Bush, Defense Secretary Robert Gates and other top military commanders. The meeting was a chance for the president to meet with his military team ahead of Petraeus' expected return to the Middle East.

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Petraeus, 54, has served two previous yearlong tours in Iraq — as commander of the 101st Airborne Division during the invasion in March 2003 and as commander of the training program for the Iraqi Army in 2004-05.

FOX News' Greg Simmons and Trish Turner and The Associated Press contributed to this report