Iraq's parliament will get a last chance to vote on Monday on authorising all non-US troops to remain in the country beyond the end of the year.
This follows last-minute negotiations after the parliament twice rejected the motion that will mainly affect British forces.
The United Nations mandate for Britain's 4,000 troops and those from Australia, Estonia, Romania and El Salvadore, runs out on 31 December.
At the weekend, lawmakers agreed there was too little time to push forward a bill, so parliament will vote on a simple resolution allowing the Baghdad government to finalise new arrangements.
The Shia-led Iraqi government has insisted that several thousand Iranians who have been living in a camp just north of Baghdad must leave the country.
The Iranians at Camp Ashraf are members of the Iranian opposition group, the People's Mujahideen.
The group is listed as a terrorist organisation in the United States and Europe, and its members have been living in exile outside Baghdad for the past two decades.
Iran has been demanding they be expelled from Iraq, but the group says it fears its members will be executed if they return home.