However, President Jalal Talabani, after meeting with US Ambassador Zalmay Khalilad, insisted the 15 August deadline for parliamentary approval would be met. He began urgent consultations with parliament leaders to head off a delay.
The formal request for a delay will be submitted to parliament on Monday, committee members said.
The decision to ask for an extension was taken during a committee meeting on Sunday, where a number of members said it was clear that major issues stood in the way of an agreement on the language of the charter.
Among the key disputes are federalism, dual nationality and the role of Islam.
Committee chairman Humam Hammoudi's recommendation of a 30-day extension was accepted, said one of the framers Bahaa al-Araji.
Al-Araji said Kurdish delegates wanted a six-month delay but the Shia and Sunni Arabs decided to ask for 30 more days.
The president's office released a statement late in the day saying that he met with members of the National Assembly and stressed the necessity of finishing the writing of the constitution at the scheduled time.
Talabani demanded that maximum efforts be exerted to reach a national accord regarding the drafting of the constitution, the statement said.
The United States had mounted considerable pressure on the Iraqis to meet the deadline. The constitution would then be put to a national referendum in mid-October with general elections due by the year's end.
US officials believe a new Iraqi constitution will help calm the fighting by encouraging the country's disaffected Sunni Arab community, which forms the core of the militants, to abandon the conflict and join the political process.