Early returns reveal that Shiites and Sunnis opted for religious parties.
Stretching newfound democratic muscle upon their first chance to elect a full-term government, Iraqis overwhelmingly threw their support behind religious parties defined along sectarian lines and ethnicity.
A bloc of Shiite religious parties close to Iran has, according to results released Tuesday, attracted the largest percentage of voters.
Here in the capital, a national barometer because it is the most diverse of Iraq's 18 provinces, the United Iraq Alliance - religious Shiites who dominated the interim government formed in May - won about 58 percent of the vote.
A Sunni Islamist alliance comprised of politicians who have defended the insurgency campaign against US troops came in next, with close to 19 percent.
Trailing in third is Iyad Allawi, a secular Shiite who was favored by the US and Iraqi moderates hoping to rise above the country's rising sectarianism. Mr. Allawi, billed as a man who could unite parties and crack down on terrorism, received less than 14 percent of the vote.
Results are still preliminary and a final count may not be announced until January. But what clearly emerges is the tendency of millions of Iraqis to turn to religious and sectarian leaders to represent their interests in the post-Saddam political arena.
With more than three-quarters of the country giving a vote of confidence to Islamist parties, last Thursday's vote raises the prospect of Iraq being more overtly religious than ever before.
The ideological orientation of the two leading vote-getters means Washington may have to work with a government of leaders who have resented the US presence here and demanded some kind of timetable for a troop withdrawal.
Clouding the election process are more than 1,000 complaints of irregularities, 20 of them considered serious enough to be deemed "red-card" violations. "The results won't be announced until those red complaints are resolved," said US Ambassador Zalmay Khalilzad.
Several Iraqi observers say they were deeply concerned over whether voters will see the results as legitimate, and raised the possibility of increased strife if claims of vote-rigging and the use of force at the polls are not answered.