The July vote on the measure now appears to have been the closest Democrats will have come to bipartisan agreement on legislation that would force President Bush to change his war strategy. And with Republicans now solidly behind the plan outlined by Mr. Bush and Gen. David H. Petraeus, the commander in Iraq, Democrats have retreated to a firm antiwar stance.

They are no longer entertaining the kind of compromise measures that some Democrats had proposed earlier this month as an attempt to attract Republican defectors and said they would instead seek opportunities to force votes that would more starkly contrast Republican support for the president with Democrats’ demands for withdrawal.

“The Republican leadership and the White House is getting them all to march in line,” said Senator Charles E. Schumer, of New York, who ranks third in the party leadership. “But it is marching further and further away from where America is. We just keep at it. It’s all we can do.” Democratic strategists and party officials said Senator Harry Reid of Nevada, the majority leader, and his colleagues decided to stop trying to strike a deal with Republicans after they found little interest on the other side and could not settle on a plan that would appeal to Republicans but was tough enough to hold Democrats together.

Jim Manley, a spokesman for Mr. Reid, said the majority leader was rebuffed repeatedly in his efforts to find consensus with the Republicans. “It became evident that Republicans were not willing to break with the president,” he said.

After the Webb proposal was defeated, Republicans failed to get 60 votes for a nonbinding resolution that said American troops should get as much respite time as possible before redeployment.

On Thursday and Friday, the Senate is expected to vote on several other war proposals by the Democrats, including one by Senator Russell D. Feingold, Democrat of Wisconsin, would require most American troops to be pulled out of Iraq by next June and would then cut financing for continuing military operations.

Another proposal by Senator Carl Levin of Michigan, the Democratic chairman of the Armed Services Committee, would require a shift of American troops away from combat by next summer. Neither has much chance of winning 60 votes.