The US Senate is expected to pass a bill on Iraq today that requires President Bush to begin bringing home an unspecified number of troops within four months.
The non-binding bill calls for the ceasing combat operations as of March 31st, 2008. Mr Bush has already said he will veto any call for a withdrawal from Iraq.
Democrats, in control of both chambers of Congress in Washington after last year's election, are moving toward a high-stakes veto fight with the Republican president over the war.
"This Congress is taking the responsible course and responding to needs that have been ignored by your administration and the prior Congress," the leaders of the two Democratic-controlled chambers, House of Representatives Speaker Nancy Pelosi and Senate Majority Leader Harry Reid, wrote in a letter to Mr Bush.
The House already passed similar legislation, a more sweeping measure last week that included a mandatory withdrawal deadline for all combat troops before September 2008.
The two sides must settle their differences and approve a final compromise bill, but Democrats said the recent votes guaranteed the president would be handed a measure imposing a timetable on Iraq.
"This war without end has gone on far too long, and we're here to end it," Mrs Pelosi said.
The legislation is the Senate's first, bold challenge of Mr Bush's war policies since Democrats took control of Congress in January. With Senate rules allowing the minority party to insist on 60 votes to pass any bill and Democrats holding only a narrow majority, Mr Reid had been unable to push through resolutions critical of the war.
AP