A vote on Rep. John Murtha's proposal likely will come in September, when Iraq commander Gen. David Petraeus delivers a long-anticipated assessment on the war and members of Congress weigh some $600 billion (EUR436.5 billion) in defense spending requested by President George W. Bush.
Under his plan, Murtha, a close ally of the House leadert, Speaker Nancy Pelosi, said that he envisions troop withdrawals to start in November and take about a year to complete.
The House has passed similar proposals in the past, including one that Bush vetoed. But Murtha said he predicts this vote will be different because of mounting voter frustration with the war and a lack of progress in Iraq.
"This is big time," Murtha told reporters of the upcoming war debate in September. "When you get to September, this is history. This is when we're going to have a real confrontation with the president trying to work things out."
Bush has not given any indication he is open to a dramatic shift or a major redeployment of troops after September. He instead has talked at length about the need to remain engaged in Iraq to fight al-Qaida and has repeatedly appealed to lawmakers for more patience.
For their part, top U.S. military officers also have indicated that the troop buildup initiated this year may be needed through the middle of 2008.
Congressional Republican leaders have been willing to support Bush so far, although they concede keeping their rank-and-file in line behind the president will become considerably tougher come September.
In response to Murtha's proposal, House Republican Leader John Boehner said Democrats were ignoring progress in Iraq.
"If they are not listening to reports from our generals today, how does anyone believe they will make an honest and objective decision in September?" Boehner said. "Our national security is not a political football, and Republicans aren't going to treat it as such."
Murtha counters that he thinks Bush and Republican members will have no choice. To maintain current troop levels through 2008, Murtha predicted that combat tours would have to be extended from 15 months to 18 months - a politically unsavory position to take on an already deeply unpopular war.
The Defense Department has said that extending combat tours of troops would be a last resort.
Murtha said he will propose his measure as an amendment to the $460 billion (EUR334.7 billion) annual military funding bill, which the House will begin debating next week and probably finish in September. The bill does not include the $142 billion (EUR103.3 billion) that Bush requested for the wars in Iraq and Afghanistan, which the House plans to consider separately.
Dividing military spending into two bills leaves open the possibility that Congress could withhold all or portions of the combat funds.
"We may decide in September we're not satisfied with what Gen. Petraeus says and we may hold it up," Murtha said.