Iraqi negotiators reached a breakthrough deal on the constitution and at least one Sunni Arab party said it would now urge its followers to approve the charter in this weekend's referendum.
Under the deal, the two sides agreed Tuesday on a mechanism to consider amending the constitution after it is approved in Saturday's referendum. The next parliament, to be formed in December, will set up a commission to consider amendments, which would later have to be approved by parliament and submitted to another referendum.
The agreement boosts the chances that the draft constitution will be passed Saturday. Shiite and Kurdish leaders support the draft and the United States has been eager to see it approved to avert months more of political turmoil, delaying plans to start a withdrawal of US forces.
In return, the agreement guarantees Sunni Arabs the ability to try later to introduce major changes they want, aimed at reducing the autonomous powers that Shiites and Kurds would have under the federal system created by the charter, negotiators said.