Senate Democrats will forge ahead with votes on anti-war measures later this week, even though most of the proposals lack the Republican support needed to advance.

As a result, Congress appears no closer to passing bipartisan legislation that could challenge President Bush’s Iraq War strategy despite a growing chorus of centrists on both sides of the aisle calling for change.

The decision by Senate Majority Leader Harry Reid, D-Nev., to hold votes on war measures that are likely to fail suggested another Democratic effort to put both parties on record yet again on the Iraq issue.

Having failed to win over Republicans on compromise measures, Democrats appeared to be returning to a hard-line approach. They had considered bringing to the floor a measure by Democrats Carl Levin of Michigan and Jack Reed of Rhode Island that would set a goal, not a ­requirement, for withdrawing most U.S. troops from Iraq in nine months. That measure will have to wait while a version with a firm deadline is put to the Senate, Reid told reporters. Three other left-of-center Democratic measures also are likely to get a vote before the Senate returns to any compromise-oriented amendments.

“We haven’t found much movement in the Republicans,” Reid said. “They seem to be sticking” with Bush.

The Iraq debate occurs as the Senate works on a $648.3 billion defense authorization bill (HR 1585). Iraq measures are being mulled as amendments, although Senate leaders are considering the possibility of moving free-standing Iraq-related legislation as well.

On Wednesday, the Senate plans to vote on whether to cut off debate on an amendment by Patrick J. Leahy, D-Vt., and Arlen Specter, R-Pa., that would restore the right of terrorism suspects to contest their incarceration or treatment by going to U.S. courts. Then it plans to vote on a second-degree amendment by Lindsey Graham, R-S.C., that would strike a portion of a pending amendment that would give detainees charged with war crimes access to lawyers and evidence against them.

After those votes, the Senate intends to move to an amendment by Jim Webb, D-Va., that would require that U.S. troops be given at least as much time at home as they spend deployed to Iraq or Afghanistan. The Webb measure, which netted 56 votes in July, is now closer to the 60 votes needed to cut off an expected Republican filibuster. Among the GOP senators who may support the measure are Specter, Lisa Murkowski of Alaska and George V. Voinovich of Ohio.

“We still need at least three Republicans to cross over,” said Senate Majority Whip Richard J. Durbin, D-Ill. “We’re working on it every day.”

The Webb measure is significant because its supporters and critics say it could reduce the number of troops available to fight in Iraq and Afghanistan.

The White House has made clear that the president would veto the measure. If he does, Webb is far from the 67 votes needed to override a veto.

Three other Democratic amendments on deck stand even less chance of overcoming filibusters, let alone overriding vetoes.

A tougher version of the Levin-Reed proposal would mandate a withdrawal of an unspecified number of troops from Iraq to begin in 90 days and would require that all troops except those needed for a more limited set of missions be withdrawn within nine months. The limited missions include targeting terrorists, protecting Iraq’s borders, training Iraqi security forces and protecting U.S. personnel and assets.

The decision to go with a stronger version of Levin-Reed, at least to begin with, addresses concerns of the more liberal members of the Democratic Party.

“We believe it’s important to vote for something we believe in first,” Levin said.

Also on the Senate’s agenda is a revised version of a troop withdrawal amendment that Reid and Russ Feingold, D-Wis., offered earlier this year. The new proposal would require troops to be withdrawn from Iraq and redeployed on the more-limited missions by the end of June 2008, Reid said.

The Senate also will consider a non-binding amendment by Foreign Relations Chairman Joseph R. Biden Jr., D-Del., that would call for an Iraq divided into Shiite, Kurdish and Sunni “federal regions” and a law to share oil revenues among them. Biden’s measure also would call for a regional conference on Iraqi peace.

Meanwhile, both Democratic and Republican moderates appear to have splintered into numerous factions on Iraq. Several proposals are circulating that are similar in intent and even provisions. But rather than compromise, their respective authors are still holding out for their own approach.

These alternatives include a measure by Susan Collins, R-Maine, and Ben Nelson, D-Neb., that would immediately limit the mission of U.S. troops in Iraq. Another, by Lamar Alexander, R-Tenn., and Ken Salazar, D-Colo., would recommend a similar mission change, plus a withdrawal of U.S. troops to begin by next year.

A third, new proposal, by Voinovich, is a binding, joint resolution that would require an unquantified reduction of U.S. forces in Iraq to begin in 120 days. It would establish as its goal a “limited presence” of U.S. forces at a date to be determined by Bush and reported to Congress in six months. The limited set of missions described in the bill is not markedly different from the tasks U.S. forces are performing today.

Adam Graham-Silverman, Kathleen Hunter and Bart Jansen contributed to this story.