Senate Democrats are planning to keep the Senate in session throughout Tuesday night to highlight Republican resistance to allowing a simple majority vote on a plan to withdraw troops from Iraq.

Harry Reid (D-Nevada), the Senate majority leader, was quoted by Tuesday's New York Times as saying that he will force lawmakers to go on record in votes around the clock until a procedural showdown Wednesday morning on a proposal to begin withdrawing troops within 120 days, with most troops out by next spring.

He said Republicans were using the threat of a filibuster, which can only be cleared with 60 votes, to protect President George W. Bush from a policy rebuke.

Republicans dismissed the Democratic tactic as a stunt and offered to speed up the clock to prevent lawmakers from having to spend the night in their Capitol offices if they did not want to miss votes.

But they did not offer an agreement to allow an up-or-down vote on the proposal, saying the 60-vote threshold had been the standard on contentious votes on the war so far this year.

Because of shifting Republican sentiment, Democratic leaders are confident they have more than 50 votes for the troop withdrawal proposal, which requires only a simple majority vote.

But to get to that vote they need to cut off debate, which will be hard to do because even some Republicans who have voiced new reservations about the war remain unwilling to vote for any provision that includes the withdrawal timeline opposed by the White House.

If the Democrats fall short, the withdrawal proposal will be dead for now and Senate Democrats will probably move on to another plan on Iraq.