The Senate on Thursday will move to jumpstart negotiations on Iraq War spending as lawmakers in both parties stress the need to clear a bill that President Bush can sign by Memorial Day.

To do so, the Senate will pass a placeholder measure on Thursday that essentially amounts to a statement of support for U.S. troops. This will enable the Senate to go to conference with the House, where the serious negotiations will begin. White House officials also will take part in those talks.

Before approving the measure, the Senate is expected to substitute the language expressing support for the troops into the House war spending bill (HR 2206).

Those votes will come one day after the Senate held three Iraq-related votes on an unrelated water resources bill (HR 1495).

Although none of the Iraq language voted on Wednesday will be part of the vehicle that moves into conference, Democrats and Republicans sought to use the vote tallies to bolster their respective viewpoints heading into the most crucial stage of the negotiations.

Unlike the first war spending proposal (HR 1591) — which had minimal Republican input and which Bush vetoed May 1 — Democrats are working this time with Republicans and the White House to reach a deal. Senate Majority Leader Harry Reid, D-Nev., and Minority Leader Mitch McConnell, R-Ky., affirmed their commitment Wednesday to providing a bill that Bush will sign.

“Sen. Reid and I agree that we ought to complete the job before Memorial Day,” said McConnell, who also noted that 100 days had passed since Bush requested the money. “And that includes getting a presidential signature.”

When asked whether he expects that the next proposal they send Bush will be something the president will sign, Reid replied: “The answer is yes, of course. And we’re going to have some heavy negotiations.”

House Republican Conference Chairman Adam H. Putnam of Florida welcomed the Senate movement, though he seemed unimpressed by the contorted legislative process involved.

“I am encouraged by what the Senate appears to be doing to go through their series of motions to get to a conferenceable position, even though, in typical Senate fashion, they [have] to go around their thumb to get to their pinkie,” Putnam said.

The House passed its version of the new emergency supplemental spending bill May 10. The proposal has drawn a veto threat, in large part because of its time-release formula, which would provide $42.8 billion for the war immediately and the remaining $52.8 billion in July, but only if Congress votes to release the second round of funding.

Aside from the Iraq policy, Senate negotiators want to send Bush essentially the same conference report as the one he vetoed earlier, according to appropriations aides. They seem to believe he will accept their higher funding level if the Iraq policy is to his liking.

House Defense Appropriations Chairman John P. Murtha, D-Pa., said he did not know how the Iraq provisions would play out in conference. “I think we haven’t sat down yet, so I don’t know what to tell you,” he said Wednesday.

The language the Senate is expected to approve Thursday as part of a Reid-McConnell substitute amendment was previously agreed to March 15, as a resolution (S Res 107) introduced by Patty Murray, D-Wash. That measure was adopted overwhelmingly, 96-2, and expresses a sense of the Senate that Congress should not take steps to undermine the safety of the armed forces.

Murray’s resolution does not by itself include any appropriations for the war or other assorted domestic items that Democrats sought to include in the vetoed spending measure and, as such, is considered a placeholder measure.

Besides the substitute amendment, no other amendments are anticipated.

Instead, the bulk of the Iraq debate has taken place the past couple days over four Iraq-related amendments that were introduced during Senate debate on the water resources bill.

A Democratic amendment by Russ Feingold of Wisconsin would have required U.S. troop redeployment from Iraq to be completed by March 31, 2008, with limited exceptions. That vote was 29-67, well below the 60 votes necessary for cloture.

Carl Levin, D-Mich., had offered an amendment to begin redeployment of U.S. troops from Iraq by Oct. 1, 2007, to be completed within 180 days — but allow the president to waive the provision. Levin withdrew it Wednesday, saying his intention had been to suggest language that could avert a veto, but that Bush’s national security adviser informed him that Bush would veto his proposal anyway.

An amendment by Republican John W. Warner of Virginia did draw a majority of votes, 52-44, but fell short of the 60 votes necessary to invoke cloture. Warner’s amendment would have directed the president to withdraw U.S. troops if the Iraqi government formally passed a resolution calling for their removal, and would have established benchmarks for the Iraqis to meet. It also would have required the president to produce reports in July and September on the Iraqi government’s progress, and unless he certified that they were moving forward, foreign aid would be withheld — but the president could waive the requirement if he justified it to Congress in writing.

Most Democrats voted against Warner’s amendment because they said the waiver provision made it essentially meaningless. Reid called it “very tepid, very weak.”

The only proposal that received enough votes to invoke cloture was one by the top Republican appropriator, Thad Cochran of Mississippi, to express the sense that Congress should clear a war funding bill by Memorial Day that Bush could sign. It was adopted by voice vote after the Senate voted, 87-9, to limit debate on the amendment.

After the votes, Democrats sought to make the case that most senators had now voted to change strategy in Iraq.

John Kerry, D-Mass., said that “the significance of these votes are that a majority of the United States Senate is now on record as wanting a change; not all in agreement as to what it will be, but Harry Reid and the conference will now hammer that out.”

Republicans, meanwhile, cited the relatively low show of support for Feingold’s amendment — even though the number of redeployment supporters has been growing.

“Only 29 members of the Senate voted for establishing a date of defeat,” said McConnell. “The Warner amendment, which I thought was a responsible middle ground, achieved 52 votes, on a bipartisan basis.”

Regardless of what happens on the war supplemental, Democrats said they would use other bills as vehicles to debate Iraq in the future.

“We’re going to have a [Department of Defense] authorization bill, we’re going to have a DOD appropriation bill, as well as the conclusion of this conference,” Charles E. Schumer, D-N.Y., noted Wednesday. “And every step has moved us closer to our goal.”

Jonathan Allen, Michael Teitelbaum and Tim Starks contributed to this story.