Iraq's leaders wrangled over limits on regional autonomy in what could be the final 24 hours of negotiations about a new Constitution, with expectations rising that they would meet a deadline to clinch a deal by today.

Parliament was summoned to a special sitting late today and several negotiators said it was likely the National Assembly would be able to start reviewing the new charter right away.

"At this meeting (of Parliament), we expect the draft Constitution will be delivered," Nasser al-Awadi, a Sunni Arab member of the constitutional drafting committee, said.

Lawmakers were summoned for 6 p.m. (1400 GMT) today.

Bahaa al-Araji, a leading Shi'ite member of the committee, also said the Constitution would be ready to be presented to Parliament by today's deadline, although talks chaired by President Jalal Talabani continued through yesterday evening.

Prime Minister Ibrahim Jaafari told reporters he was "optimistic" about an agreement today, while his spokesman and adviser, Laith Kubba, told CNN: "From what I hear, there is an agreement and the document will be submitted on time."

The main sticking point has been arguments over the extent of regional autonomy, particularly for Kurds and Shi'ites, as well as Shi'ite demands for a bigger role for Islam in the law.

Clinching a timely deal is a key goal for President George W. Bush, who says the process will undermine rebels among the Sunni Arab minority and aid US plans to hand power to Iraqis.