BAGHDAD -- Iraqis vote today on a new constitution that many believe could further divide the country among ethnic and religious lines, while others see it as the first draft of a blueprint for eventual coexistence among Sunni and Shi'ite Arabs and ethnic Kurds.
The visceral debate played out yesterday, after Friday prayers, in the doorway of the 14th of Ramadan Mosque, just across the street from where US troops and elated Iraqis pulled down the statue of Saddam Hussein after the US invasion two and a half years ago.
Like Iraqis everywhere, the Sunni worshipers sparred over the meaning of their vote. Some said casting a vote -- for or against the constitution -- would be their biggest personal role so far in deciding the country's fate; others dismissed it as a necessary evil, a pragmatic step to protect their interests in a political process tainted by US occupation.
All agreed that for better or worse, today would be a defining moment for the country and its disaffected Sunni minority.
After a conflict that has cost nearly 2,000 American lives and killed thousands of Iraqis, voters are being asked for their verdict on a constitution that would enshrine freedoms unheard of in Hussein's Iraq and much of the Arab world, including ''principles of democracy" and free speech; set up a representative government; and seek to protect Iraq's disparate sects and ethnic groups from a repeat of Hussein's predations.
But the vote is occurring in a period of unrelenting violence from a Sunni-led insurgency, amid growing ethnic and religious tensions, and in an atmosphere of grating disappointment with the inability of the government and its US backers to provide security, electricity, jobs, and services.
And the process of drafting the constitution has exacerbated rifts in Iraqi society. Some Iraqis fear it goes too far to enshrine Islam as the basis of government; some say it doesn't go far enough. Others worry that the charter could increase ethnic strife; many Sunnis believe it treats them unfairly and fear its provisions for federalism will allow the creation of oil-rich Shi'ite and Kurdish ministates that leave Sunni areas isolated.
The White House has presented the referendum as a major chance to defuse the insurgency by drawing Sunnis into politics. But a US diplomat, speaking anonymously under embassy policy, said yesterday that the constitution vote alone will probably have little effect on the insurgency. What's more important, he said, is that many Sunnis now say they will vote in the elections to be held in December, if the constitution passes, for a legislature that would serve four years.
Sunnis, who make up about 20 percent of the population, largely sat out elections for the interim assembly 10 months ago and as a result were nearly shut out of the body that drew up the constitution.
These days, Sunnis aren't debating whether to vote, but how to vote. Today's referendum is particularly perplexing for Sunnis. At the mosque, Sunnis once afraid to utter the smallest criticism of Hussein argued loudly over a surprising reversal this week by the Iraqi Islamic Party, the one Sunni party that has consistently taken part the in US-sponsored political process.
After campaigning hotly against the constitution for months, the party decided this week to support it, in return for a provision that would make it somewhat easier to amend the constitution next year.
Atheer Ali, 47, an engineering professor, declared after the sermon yesterday that there was only one explanation for the shift: ''They were promised posts" in the next government, Ali said.
He had just listened to the imam, a friend of his, defend the Islamic Party's move.
''When the Prophet went to Medina, the first thing he did was reach a truce with the Jews and the non-Muslims, and this became the constitution of Medina," the imam, Qusay al-Ramah, had intoned. ''Do we want a disturbed country in which each one eats the other, an unstable, dangerous country with no security?"
But after prayers, a dozen men surrounded him and railed against the constitution.
''It divides the country in a very distinctive sectarian image," said Rakan Salem, 50, raising his voice.
''If you want to vote 'no,' vote 'no,' " Ramah said. ''There is no objection."
Yesterday, insurgents weighed in by setting off a bomb outside Islamic Party headquarters and torching a party office in Fallujah. And last night, insurgent attacks caused blackouts in much of Baghdad.
Sunnis seem divided on what would best serve their interests: vote for the constitution they almost universally dislike to avoid an outright rift in society or vote ''no" in a united bloc to show their political strength.
The constitution will fail if two-thirds of those who vote in any three provinces reject it. Sunnis are the majority in four provinces but would have to trounce highly motivated Shi'ite and Kurdish voters to pull off the veto.
The last minute, US-brokered deal was hailed as a major concession by Shi'ites and Kurds to build consensus.
But Ali -- echoing many Sunni groups who rejected the deal -- called it a ploy to trick Sunnis into voting 'yes' and missing their one chance, albeit a slim one, for significant change in the constitution.
If Sunnis do sink the draft today, a new temporary assembly will be elected for one year, to rewrite the constitution from scratch. In that event, Sunnis would probably turn out to much higher numbers than for the last assembly election.
If the constitution passes, the new legislature elected in December can make changes, according to the compromise provisions.
Echoing the Islamic Party, Ramah told his flock that was a ''safety valve" that makes the constitution ''temporary."
But changing it won't be that easy. Even with the compromise, it takes a 51 percent vote in the new legislature to propose a change -- a number Sunnis are unlikely to be able to muster even if they turn out in force. Then, any change must go to another referendum -- and Shi'ites and Kurds could easily veto it with two-thirds of voters in three provinces.
''Practically speaking, there will be no change in the constitution," Ali said.
''Let us vote 'no' and let what happens happen," said Amar Sultan, a civil servant. ''There are more of them [the Shi'ites] than us, there is nothing real in their offer."
Shi'ite and Kurdish leaders yesterday appealed to voters to turn out in great numbers.
Al Furat, a Shi'ite-sponsored television channel, yesterday played a video with the tune and rhythm of religious chants that commemorate Imam Hussein, one of Shi'ite Islam's holiest figures.
''All the people write the words of light: Yes to the constitution," a man sang over photos of mass graves of Shi'ites slaughtered by Hussein's troops, of bodies in white shrouds, of weeping women in black Shi'ite abbayas.
Kurdish slogans emphasize that the charter enshrines Kurdish autonomy.
Around the corner, a knot of young Sunnis sat mulling their options.
''We will vote, but we don't know if it matters if we say 'yes' or 'no,' " said Amar Ali, 22, as he playfully carved into a watermelon rind the words, ''Made in China."
The young men boycotted the last elections, but didn't like the results: ''A war against Sunnis," said Mohammed Ibrahim, 22, a veterinary student.
Chin on hand, his brother Firaz, 24, an engineering student, said he was confused after the sermon and the Islamic Party's reversal.
''We are surprised," he said. ''I think we'll vote against it. If I get up early enough."
Globe correspondent Sa'ad al-Izzi contributed to this story.