A defiant, Democratic-controlled Senate is calling for the withdrawal of US combat troops from Iraq within a year, propelling Congress closer to an epic, wartime veto confrontation with President George W. Bush. Thursday's 51-47 vote for the bill to finance the war effort while trying to bring the troops home was largely along party lines. Also, like the House of Representatives' passage of a separate, more sweeping challenge to Bush's war policies a week ago, the Senate bill fell far short of the two-thirds margin needed to overturn the president's threatened veto. It came not long after Bush and House Republicans made a show of unity at the White House. "With passage of this bill, the Senate sends a clear message to the president that we must take the war in Iraq in a new direction. Setting a goal for getting most of our troops out of Iraq is not - not, not - cutting and running," said Democratic Sen. Robert C. Byrd, the oldest member, shortly before the vote. Passage cleared the way for negotiations to combine the House and Senate bills into a compromise package.