The Senate narrowly rejected a Republican amendment that would have removed the troop withdrawal clause from a bill on military funding.

The vote is a boost for the Democrats and a setback for US President George W Bush, who has vowed to veto any bill setting out a timetable for withdrawal. The House of Representatives also backed withdrawal in a vote last week.

The House bill, which imposes a 31 August 2008 deadline for pulling troops out, was passed narrowly by 218 votes to 212 on Friday.

A final Senate vote on the whole funding bill will take place later this week. It will need the support of a dozen Republicans to pass.

Senate Majority Leader Harry Reid called the vote a significant step forward and a pointed message to Mr Bush.

"With this vote, the Senate is giving our troops the resources they need in combat - including a strategy in Iraq worthy of their sacrifices," he said. "The president must change course, and this legislation gives him a chance to do that," he said.

But there were no concessions from the White House.

Mr Bush "is disappointed that the Senate continues down a path with a bill that he will veto and has no chance of becoming law," his deputy press secretary, Dana Perino, said in a statement.

A presidential hopeful, Republican John McCain, said that setting a schedule for pulling troops out of Iraq would encourage insurgents.

Reuters