The US says it is considering a draft agreement with Iraq on the role of its troops there after the UN mandate for their presence expires later this year.
US 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Details have not been released, but officials say it would see US combat forces withdrawn from Iraqi towns and cities by the middle of 2009.
Details have not been released, but officials say it would see US troops withdraw from Iraq by the end of 2011.
The troops would withdraw completely from Iraq by the end of 2011, they add.
Mr Gates is said to be briefing key members of Congress on the deal, although their approval is not needed.
Defence Secretary Robert Gates has begun briefing key members of Congress, although their approval is not needed.
But the draft does need approval on the Iraqi side, which correspondents say could prove difficult.
Secretary of State Condoleezza Rice is also said to be pressing Iraqi leaders to accept the deal.
On Wednesday, the Iraqi government said it was considering the draft because a compromise had been reached on the issue of immunity for US military personnel and contractors.
Any deal must be approved by the Iraqi cabinet, the three-man Presidency Council, and critically, by the Council of Representatives.
Immunity issue
The current UN mandate for US-led coalition forces in Iraq expires on 31 December. About 144,000 of the 152,000 foreign troops deployed there are US military personnel.
The current UN mandate for US-led coalition forces in Iraq expires on 31 December. About 144,000 of the 152,000 foreign troops deployed there are US military personnel.
I don't think the [defence] secretary would be making phone calls in support of the document if he didn't believe it adequately protected our forces Pentagon spokesman Geoff Morrell
US officials say the deal would see combat forces withdrawn from Iraqi towns and cities by the middle of 2009, and could see US troops withdraw completely by the end of 2011.
The BBC's Richard Lister in Washington says major obstacles to an agreement on extending the mandate have included how long US troops would stay, and whether they would continue to be immune from prosecution in Iraq.
However, a Pentagon spokesman said the complete withdrawal "will only be followed if the conditions on the ground provide for it".
The Iraqi government has publicly insisted on a clear timeline for withdrawal, and US officials said the current draft included a timeline for US withdrawal before the end of 2011.
The Bush administration has long opposed the idea of a timeline for the withdrawal of US troops.
It is also said to grant Iraqi judicial authorities limited ability to try US troops and contractors for major crimes committed off-duty or off-base - and only then if a joint US-Iraqi committee agreed.
Immunity issue
The government in Baghdad believes the current immunity from Iraqi prosecution by granted to US troops and contractors by the former Coalition Provisional Authority (CPA) undermines Iraqi sovereignty.
Mr Gates, Secretary of State Condoleezza Rice and President George Bush's national security adviser, Stephen Hadley, are said to be reaching out to key members of the House of Representatives and the Senate.
Misgivings
Ms Rice also is also said to be pressing senior Iraqi leaders to accept the deal.
However, many members of Congress are concerned about allowing Iraq's judicial system to have even limited authority over US troops.
The first test for the agreement is at a meeting of the Political Council for National Security on Friday.
The body brings together all the top Iraqi political figures, including the heads of parliamentary blocs.
I am sceptical of any agreement that would subject US servicemen and women to the jurisdiction of Iraqi courts in the middle of a chaotic war Carl LevinUS senator
If it wins approval there - and that's not expected to be automatic or trouble-free, says the BBC's Jim Muir in Baghdad - that would imply that endorsement by parliament, and the cabinet should follow on relatively smoothly.
Senior Iraqi officials involved in the negotiations say they believe all the outstanding issues have been settled.
The Iraqi government believed that the current immunity from prosecution by granted to US troops and contractors by the former Coalition Provisional Authority (CPA) undermined Iraqi sovereignty.
The new draft is said to grant Iraqi judicial authorities limited ability to try US troops and contractors for major crimes committed off-duty or off-base - if a joint US-Iraqi committee agrees.
It is a move that worries some members of the US Congress.
"I am sceptical of any agreement that would subject US servicemen and women to the jurisdiction of Iraqi courts in the middle of a chaotic war," Senator Carl Levin, chairman of the Senate Armed Services Committee, told the Associated Press.
"I am sceptical of any agreement that would subject US servicemen and women to the jurisdiction of Iraqi courts in the middle of a chaotic war," Senator Carl Levin, chairman of the Senate Armed Services Committee, told the Associated Press.
A Pentagon spokesman said the administration was not concerned by the draft agreement and that Mr Gates was currently calling Congressional leaders to explain the details.
However, a US spokesman said Mr Gates believed it offered adequate protection for US forces in Iraq.
"I don't think the secretary would be making phone calls in support of the document if he didn't believe it adequately protected our forces in Iraq," Geoff Morrell said, adding that it included both combat and legal protections.
Another difficulty that remains is that any agreement for the continuing presence of US troops in Iraq is anathema to some of the political groups in Iraq, our correspondent says.
Our correspondent says the two sides have been close to a deal before, but the fact that the Bush administration is now briefing key members of Congress on the details of this document suggests the negotiations may now have run their course.
The faction loyal to the militant Shia cleric, Moqtada Sadr, is bitterly opposed and a big protest demonstration has been called for Saturday.
But as they are not required to formally endorse this agreement, the biggest question mark remains over whether the Iraqis will, he adds.
If there is no final agreement by the end of the year, the two sides would have to go back to the UN to renew its mandate.
What is your opinion on the draft agreement? Are you serving in Iraq?
Send your comments using the post form below, or text 00 44 7725 800 100.
In most cases a selection of your comments will be published, displaying your name and location unless you state otherwise in the box below.
