Senate Minority Leader Trent Lott of Miss., left, accompanied by Sen. John Ensign, R-Nev., center, and Sen. John Cornyn, R-Texas, gestures during a news conference on Capitol Hill in Washington, Thursday, March 29, 2007, to discuss the Iraq Supplemental spending bill. [AP]

WASHINGTON - A defiant, Democratic-controlled Senate approved legislation Thursday calling for the withdrawal of U.S. combat troops from Iraq within a year, propelling Congress closer to an epic, wartime veto confrontation with US President Bush.

The 51-47 vote was largely along party lines, and like House passage of a separate, more sweeping challenge to the administration's war policies a week ago, 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.

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"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 Sen. Robert C. Byrd, D-W.Va., shortly before the vote. Passage cleared the way for negotiations on a compromise with the House.

Senate Republican leader Mitch McConnell of Kentucky rebutted quickly. "Nothing good can come from this bill," he said. "It's loaded with pork that has no relation to our efforts in Iraq and Afghanistan, and it includes a deadline for evacuation that amounts to sending a `Save the Date' card to al-Qaida."

Several blocks away, the commander in chief stood with Republican House members and told reporters they were united. "We expect there to be no strings on our commanders and that we expect the Congress to be wise about how they spend the people's money," he said.

In private, Bush was at least as emphatic, according to participants at a closed-door session in the White House East Room with the GOP rank and file. "He said he will veto a bill that comes to his desk with too many strings attached or too much spending," said one official in attendance, speaking on condition of anonymity because the meeting was closed to the press.

While both sides have spoken positively about a need for compromise, there also was strong political pressure within both parties for a veto fight.

Democrats are under pressure to challenge Bush on the war following their victories in last fall's elections. At the same time, Republicans say Bush will blame anti-war lawmakers if money begins to run short for the troops in the field and will accuse them in any event for ceding ground to the terrorists in the Middle East.

Gen. Peter Pace, chairman of the Joint Chiefs of Staff, told the House Defense Appropriations Committee during the day that a delay in funding would have a chain reaction that could keep units in Iraq longer than planned. He said if the bill is not passed by May 15, the Army will have to cut back on reserve training and equipment repairs, and possibly delay the formation of units needed to relieve those deployed.

The House-passed measure requires the withdrawal of combat troops by Sept. 1, 2008. The Senate bill mandates the beginning of a withdrawal within 120 days, and sets a nonbinding goal of March 2008, for its completion.

Both bills contain more than $90 billion for the military to continue operations in Afghanistan as well as Iraq, where more than 3,200 U.S. troops have lost their lives in four years of combat. Money for domestic programs pushes the measures' totals above $120 billion.

If anything, it is more likely that House and Senate Democrats will have trouble in forging a compromise among themselves than that they will flinch from a confrontation with the White House. Mindful of the need to assure a flow of funds, Rep. John Murtha, D-Pa., said Congress may consider passing monthlong spending bills while it challenges Bush over his war policy.

There is a strong reluctance among the rank and file to approve money for the war without attaching conditions to force a change in policy, and lawmakers said that situation portended a House-Senate compromise that would include provisions Bush has rejected.

"I don't think the leadership will give in. I don't think they can give in," said Rep. Jim Moran, D-Va. "We have very strong feelings among members. And the real strong pushback would come from voters."

"I'm not willing not to have input," said Murtha, who has emerged in the past year as one of the Democrats' most vocal critics of the war.

Nor is the war the only issue in dispute.

Both bills contain in excess of $20 billion in domestic spending that the president wants stripped out, including large amounts for politically popular programs such as disaster aid to farmers and money for victims of hurricanes Katrina and Rita.

"I think we would be able to sustain a veto on that basis alone," said Sen. Trent Lott of Mississippi, the second-ranking Republican. House GOP Leader John Boehner of Ohio addressed the same issue in the meeting with Bush. According to one participant, Boehner said there might be a perception among White House officials that the House would not sustain a veto based solely on spending. Boehner said he thought that fear was ungrounded, and the rank and file responded with a standing ovation, according to this participant.

There was no suspense in the Senate's vote, following a test earlier this week in which Republicans had sought to strip out the nonbinding timeline for a troop withdrawal. There were 48 Democrats and two Republicans, Chuck Hagel of Nebraska and Gordon Smith of Oregon, voting for the measure, along with Sen. Bernie Sanders, a Vermont independent. Among the supporters, only Sen. Mark Pryor, D-Ark., had voted to jettison the timeline earlier in the week.

The votes in opposition were cast by 46 Republicans and Sen. Joseph Lieberman of Connecticut, an independent Democrat.