The Senate passed a roughly $123 billion supplemental war spending bill today by a 51-47 vote, paving the way for what lawmakers hope will be a speedy conference.

President Bush has vowed to veto the bill (HR 1591) because it contains language calling for the withdrawal from Iraq of most U.S. troops by a year from now.

Bush also has said he will veto the House version, which would require the withdrawal of troops by the end of August 2008. That bill also contains waiveable readiness standards.

Senate Foreign Relations Chairman Joseph R. Biden Jr., D-Del., said he expected serious discussions in the House-Senate conference on final withdrawal language.

“I think it requires people to focus on what the endgame is,’’ Biden said.

“Obviously, I like the Senate language better. The House is not bad. What is better about ours is it sets a goal” that gives the president flexibility, he said.

Two Republicans, Chuck Hagel of Nebraska and Gordon H. Smith of Oregon, voted with Democrats to pass the bill.

Before passage, the Senate adopted 98-0 an amendment that boosted the bill’s topline figure by $1.5 billion to buy 2,500 additional military vehicles.