The draft deal to replace a UN mandate expiring this year calls for US combat forces to withdraw by the end of 2011 and includes US concessions on jurisdiction over its troops accused of "serious crimes" while off duty or off base.
The Iraqi cabinet decided on Tuesday to seek certain revisions to the draft, triggering warnings from senior US military and political figures about the risks of not agreeing to a deal.
The United States has accused Iran of "undermining" the deal, with Condoleezza Rice, the US secretary of state saying: "I think the Iraqis can defend their interests without the Iranians, thank you very much."
"What the Iranians were doing was arming special groups in the south who were killing innocent Iraqis. So frankly I don't take these comments very seriously," she said.
Rice also reiterated that the security pact - that has been the subject of months of difficult negotiations with the Iraqis - was "a good agreement".