Sunni Arab support is vital to the lawmakers who gather inside the most heavily fortified area of the capital, trying to ignore assassination attempts, death threats and suicide attacks as they wrangle over sensitive charter details and sometimes give way to shouted arguments.
Iraq's 275-seat parliament has until mid-August to adopt a new constitution that hasn't yet been written, must be acceptable to Iraq's voters, and is expected to deal with the tough issues of the role of Islam in public life and the type of electoral system Iraq should have.
The document will face a nationwide vote two months later. If adopted, it will provide the basis for a new election to be held by December.
President Jalal Talabani, a Sunni Kurd, responded Thursday to threats by Sunni Arabs to boycott the process unless they were given more committee seats, and unless their members were allowed to vote.
The latest move to lure the reluctant Sunni Arab minority into the political process came amid reports that the Iraqi government and US Embassy were both engaged in backchannel negotiations designed to get the Sunni-dominated insurgents involved in the political process.