Saturday's session is being shown live on Iraqi national television and has been orderly so far. Chaotic scenes marred debate earlier this week when opposition lawmakers loyal to Shiite leader Muqtada al-Sadr disrupted the proceedings.
Defense Minister Abdul-Qader al-Obeidi has spoken in support of the deal. He says a premature departure of U.S. forces will expose the country to serious security threats.
A vote on the proposal is scheduled for Monday. But presidential spokesman Naseer al-Ani says the vote might be delayed until after the Muslim feast of Eid al-Adha, which falls in the first week of December.