Senate Democrats are revising their major war legislation to attract votes to pass and potentially launch a withdrawal of U.S. forces from Iraq by year’s end.

First, the author of the main Senate Democratic measure that would withdraw U.S. forces from Iraq is considering removing from the proposal a deadline for completing the redeployment, in an effort to attract enough Republican votes to pass the measure.

Michigan Democrat Carl Levin, chairman of the Senate Armed Services Committee, said in an interview the Senate could vote this month on a measure he wrote with Jack Reed, D-R.I., that would begin in 120 days the withdrawal of all but a limited set of forces. He said he may remove the deadline of April 30, 2008, for completing the process, if it can net additional GOP votes. In July, Democrats fell eight votes short of overcoming a filibuster of the measure.

“If we can pick up some more Republican support, it’s certainly worthy of consideration,” Levin said of turning the spring deadline into a goal, not a firm requirement. “We would keep the principle, which is that we would mandate the beginning of a reduction of American forces. That is the heart of the matter.”

In addition, Sen. Ken Salazar, D-Colo., said in an interview he will ask Sen. Lamar Alexander, R-Tenn., and the other 12 bipartisan cosponsors of a bill (S 1545) that would implement the Iraq Study Group’s recommendations to include in it — for the first time — a requirement that U.S. troops begin to withdraw from Iraq, probably before the year’s end. Senate Majority Leader Harry Reid, D-Nev., and other Democrats had criticized the Salazar-Alexander measure for not forcing the administration to begin or end a withdrawal. The measure as currently written sets a goal of the first quarter of 2008 for completing a withdrawal of most forces.

Salazar said he wants to “explore with some of our colleagues the concept of including in there at least some timelines for beginning a withdrawal.

“Those are conversations we’ll have, I’m sure, as the next week unfolds.”

The Levin and Salazar statements are the first firm indication that Senate Democrats are abandoning an all-or-nothing strategy on Iraq and are considering compromises that could become law.

Both their modified bills would reflect the recommendation of John W. Warner of Virginia, a leading Republican voice on national security, that the president should begin a withdrawal by year’s end A-— without a deadline for completing it. As a result, moderates in both parties appear to be moving toward consensus that Congress should mandate at least the beginning of the end of U.S. involvement in Iraq. If the consensus includes enough senators, it could result in legislation that can overcome filibusters and potentially even override a presidential veto.

“The president has repeatedly said we are not going to be there forever,” Warner said on CNN on Aug. 31. “Put some teeth in it.”

It appears House Democrats also intend to continue forcing votes on measures that would see firm withdrawal deadlines.

Over the next two weeks, Defense, foreign policy and intelligence committees will hold a series of hearings that will look in detail at reports that document progress in Iraq.

Congress will consider the following:

• The Government Accountability Office (GAO) will offer a report on Iraqi progress at meeting certain measures of political, economic and military progress. Contrary to the growing perception that the buildup of U.S. forces has tamped down violence in Iraq, the GAO reportedly has found that U.S. agencies differ on whether violence there has dropped.

• Retired Marine Corps Gen. James L. Jones Jr. will testify about a congressionally directed study he has led of U.S. training and equipping of Iraqi security forces.

• Army Gen. David H. Petraeus, the commander of forces in Iraq, and Ryan Crocker, the U.S. ambassador there, will offer their assessment of the war’s status. They are expected to say that military progress in Iraq has been significant in recent months and will pave the way for the lagging political arena to catch up. That is also President Bush’s message, and the White House will undoubtedly reiterate it in a report due to Congress by Sept. 15.

It is all but certain that neither chamber will take up Iraq legislation until after Petraeus, Crocker and the White House have delivered their assessments.

If, as expected, the Senate takes up the defense authorization bill (HR 1585) as early as the week of Sept. 17, it will certainly debate varied Iraq proposals. Reid has spoken with senators from both parties about the Iraq issue. He has talked, for example, with Democrat Jim Webb of Virginia about trying to get another Senate vote on Webb’s proposal that would require that U.S. troops spend at least as much time at home as they spend deployed. Like the Levin-Reed measure, Webb’s proposal failed previously to overcome a filibuster.

Also on the Senate’s agenda in the coming weeks are the fiscal 2008 Defense appropriations bill (HR 3222) and a war supplemental spending measure.

Democrats’ challenges have grown in recent weeks as reports of military progress from the front have taken some steam out of the calls for change.

Still, the House is likely to vote in the weeks to come on a bill (HR 2451) by Appropriations Chairman David R. Obey, D-Wis., and Jim McGovern, D-Mass., that would force a withdrawal starting in 90 days and ending by June 30, 2008. It would prohibit U.S. funding thereafter of any military operations other than fighting terrorists, training Iraqi forces and protecting U.S. personnel.

In May, the House agreed to a rule on the fiscal 2007 supplemental (PL 110-28) that would make the Obey-McGovern measure in order as the first amendment to the fiscal 2008 war spending bill.

Barbara Lee, D-Calif., co-founder of the Out of Iraq Caucus, has drafted a similar measure that would not allow for such exceptions, only permitting funding to withdraw troops or protect the ones still there.

Because the House has already passed both its Defense appropriations and authorization measures, its main forum for debate on Iraq will be the war spending measure. Estimated to total nearly $200 billion, the final supplemental request is not expected on Capitol Hill until after Sept. 17, administration and congressional officials said.

House Speaker Nancy Pelosi, D-Calif., made a plea for more votes on Iraq legislation this fall during an Aug. 23 conference call with fellow Democrats. But she did not lay out a specific course of action, aides and members said.

Pelosi told the caucus the House also may vote on a measure (HR 3087) by Democrat John Tanner of Tennessee that would require the administration to report to Congress on plans for withdrawing troops. Liberals have opposed the measure because they think it would provide a refuge for Republicans to criticize the war without ending it.

Alan K. Ota contributed to this story.