Iraqi voters are choosing 275 members of a national assembly, whose key task will be to debate and approve a new constitution. They are also voting for members of 18 provincial assemblies and the autonomous Kurdish parliament in the north.
The national assembly will pick a new government to succeed the interim administration now in power, which was formed last year by the U.S.-led occupation authority, in consultation with the United Nations.
The assembly is meant to be dissolved and a new parliament elected by the end of this year, according to terms that will be set by the new constitution.
Sunday's election is being conducted on a proportional-representation basis, with individual parties and coalitions of smaller groups putting forward lists of candidates for the assembly. There is one national ballot, without constituencies, from which voters choose a preferred candidates list.
Election officials say seats in the assembly will be allocated according to the proportion of votes won by each candidates' list. There also is a requirement that one-fourth of all seats be given to women.
