The dispute means that national polling scheduled for January is almost certain to be delayed.

Vice President Tariq al-Hashemi, a Sunni Arab, had vetoed the law because he wanted more seats for Iraqis abroad, most of whom are Sunnis. Iraq's parliament amended the law with the backing of Shiite and Kurdish legislators, but Sunni Arabs said they would get even fewer seats with the change.

On Tuesday, al-Hashemi's office said he would deal with the law the same way that he dealt with the last one.