United States defence chief Robert Gates is seeking support from politicians on a draft deal to extend the US mandate in Iraq, which expires later this year.
Details have not been released, but officials say it would see US troops withdraw from Iraq by the end of 2011.
Mr Gates is said to be briefing key members of Congress on the deal, although their approval is not needed.
But the draft does need approval on the Iraqi side, which correspondents say could prove difficult.
The current United Nations mandate for American-led coalition forces in Iraq expires on 31 December. About 144,000 of the 152,000 foreign troops deployed there are US military personnel.
US officials say the deal would see combat forces withdrawn from Iraqi towns and cities by the middle of 2009, and could see US troops withdraw completely by the end of 2011.
However, a Pentagon spokesman said the complete withdrawal "will only be followed if the conditions on the ground provide for it".
The Bush administration has long opposed the idea of a timeline for the withdrawal of US troops.