Polls Close in Iraq

But that did not stop insurgent groups from launching a concerted voter intimidation campaign in many areas of the country, particularly in the so-called Sunni Triangle north and west of Baghdad, where leaflets were passed out in the days before the election threatening death to anyone who voted. Underscoring the message, in the run-up to the referendum, militants staged at least five attacks on the offices of the Iraqi Islamic Party, an influential Sunni group that publicly backed passage of the constitution, and the homes of some of its leaders.

Under the terms of the referendum, the constitution would be approved if a simple majority of those casting ballots vote in favor of it, which seems a near certainty. It was drafted principally by Shiite and Kurdish leaders, whose people account for about 60 and 20 percent, respectively, of Iraq's 27 million people, and they have strongly urged their followers to vote "yes." However, there is also a veto provision that was designed to protect Iraq's minority communities: if two thirds of the voters in three of Iraq's 18 provinces vote against the constitution, the referendum fails.

That has raised the possibility that the minority Sunni Arabs, who comprise about 20 percent of the country's population and who have a majority in at least three provinces, could ban together to vote down the constitution. But 11th hour changes to the proposed document this week by Iraq's parliament won the support of several Sunni political groups and influential leaders, which analysts, diplomats and politicians here say could split the Sunni opposition enough to assure the referendum's success.

Results are expected in two or three days, with uncertified final results scheduled to be announced Oct. 20.

Sunnis were particularly concerned that the constitution permits such strong regional autonomy that Iraq could eventually break up, with Kurds and Shiites creating oil-rich countries in the north and south, and Sunnis being relegated to the impoverished west and center of Iraq. Instead of unifying and pacifying Iraq, they said, the constitution as written could spark a bloody civil war.

That spawned this week's changes to the constitution, which allow for the next parliament, which is scheduled to be elected in December, to make amendments to the charter and put them to voters in another referendum next year. If today's referendum is defeated, a new interim parliament will be elected in December to draft another proposed constitution.

Iraqi television showed live pictures of Kurdish President Jalal Talabani and Shiite Prime Minister Ibrahim Jafari being among the first to cast ballots at a station inside Baghdad's heavily fortified Green Zone.

"The constitution will pave the way for national unity," Jafari told reporters. "It is an historic day, and I am optimistic that the Iraqis will say 'yes.' "

While concrete blast barriers were erected around many polling stations to protect voters from attack, in Falluja, site of some of the worst fighting of the war, the centers were largely unfortified and were guarded by local citizens and tribal sheikhs

Mohammed Abdul Khaliq, director of the city's 38 polling places, said in a telephone interview that about 7,500 people had arrived to cast ballots in the first 30 minutes.

Muhammed Jamaili, manager of the electoral commission in Fallujah, said later that 93 percent of the city's 257,000 registered voters participated in the referendum.

Falluja resident Najiya Ahme Ali, 55, said she voted against the constitution "for the sake of my son, who was killed by [top Al Qaeda in Iraq leader Abu Musab] Zarqawi because he was a translator for the Americans." She said she voted no "because the religious clerics issued [orders] to vote against the constitution as it divides Iraq, and I trust them."

Despite vows that U.S. soldiers would maintain a low profile, U.S. Marine Humvees in Ramadi were blaring tape-recorded messages from loudspeakers urging people to vote from 7 a.m. to 5 p.m. The messages warned that any private vehicles and motorcycles spotted breaking the ban on travel in the streets would be shot at.

In Kirkuk, about 150 miles north of the capital, turnout was divided early in the day, with large numbers of voters casting ballots in the Kurdish areas of the city, and polling stations nearly empty in its Arab and Turkoman neighborhoods.

At the Kindi polling station, where voters lined up long before opening in January parliamentary elections, no one had cast a ballot in the first 45 minutes of voting on Saturday, elections officials at the center said. The streets outside were empty except for military patrols and checkpoints.

In Sulaymaniyah, a Kurdish-controlled city in northern Iraq, turnout was light in the first hours of voting. At the Kanes Kan elementary school polling center, only four people waited in line to vote around 8:30 a.m. Alan Azit, 26, an election coordinator at the school, said turnout was much heavier in the early hours of voting on Jan. 30 when Kurds went to the polls to elect both a new central Iraqi government and a regional government. "It's less because there are no political parties included, and people aren't engaged if the political parties are not part of the election," he said.

In Baghdad, 70-year-old Hussein Rustam walked slowly to polling center 65001 in Karrada, a heavily Shiite neighborhood, and arrived two minutes before opening. A machine gun nest was perched atop the building. He negotiated the snaking spools of razor wire and concrete blast barriers outside the entrance, then was searched by soldiers as officials from the Electoral Commission studied his identification.

"This is only a first step on the long road to build the constitutional process," he said. "And we should all take part in the process, because Iraq is home for all and we all must agree to live together."

Finer contributed from Najaf. Staff writers Steve Fainaru in Balad, Jackie Spinner in Sulaymaniyah, and special correspondents K. I. Ibrahim in Baghdad, Dlovan Brwari in Mosul, Salih Saif Aldin in Tikrit, and Saad Sarhan and Naseer Nouri in Najaf contributed to this report.