Iraqi officials are still counting votes and verifying results from Saturday's referendum, with partial results suggesting the draft constitution will be approved.
Iraq's Independent Electoral Commission says it will take random samples from some provinces to examine for possible irregularities.
President Bush praised Iraqis for voting despite threats of insurgent attacks. But U.N. Secretary General Kofi Annan says it is too soon to say if the draft constitution will bring Iraq together or widen divisions between its Shi'te, Sunni and Kurdish communities.
In other developments, a U.S. airstrike killed 20 people the military says were planting roadside bombs near Ramadi. Other coalition operations in Al Anbar province on Sunday killed what U.S. officials said were 50 more suspected terrorists. But residents say half of the dead were civilians.
Some information for this report provided by AP and Reuters.