Iraqi negotiators finished the new constitution Sunday and referred it to the voters but without the endorsement of Sunni Arabs (search), a major setback for the U.S. strategy to lure Sunnis away from the insurgency and hasten the day U.S. troops can go home.

The absence of Sunni Arab endorsement, after more than two months of intensive negotiations, raised fears of more violence and set the stage for a bitter political fight ahead of an Oct. 15 nationwide referendum on the document.

A political battle along religious and ethnic lines threatened to sharpen communal divisions at a time when relations among the Shiites, Sunni Arabs and Kurds appear to be worsening.

Sunni negotiators delivered their rejection in a joint statement shortly after the draft was submitted to parliament. They branded the final version as "illegitimate" and asked the Arab League (search), the United Nations and "international organizations" to intervene against the document.

Intervention is unlikely, however, and no further amendments to the draft are possible under the law, said a legal expert on the drafting committee, Hussein Addab (search).

"I think if this constitution passes as it is, it will worsen everything in the country," said Saleh al-Mutlaq, a Sunni negotiator.

President Bush expressed disappointment that the Sunnis did not sign on but pinned his hopes on the referendum.

"Some Sunnis have expressed reservations about various provisions in the constitution and that's their right as free individuals in a free society," Bush said in Crawford, Texas.

He said the referendum was a chance for Iraqis to "set the foundation for a permanent Iraqi government."

But the depth of disillusionment over the charter in the Sunni establishment extended beyond the 15 negotiators, who were appointed to the constitutional committee in June under U.S. pressure.

The country's Sunni vice president, Ghazi al-Yawer, did not show up at a Sunday ceremony marking completion of the document. When President Jalal Talabani said that al-Yawer was ill, senior government officials including Deputy Prime Minister Ahmad Chalabi howled with laughter.

"The constitution is left to our people to approve or reject it," said Talabani, a Kurd. "I hope that our people will accept it despite some flaws."

A top Sunni who did attend the ceremony, parliament speaker Hajim al-Hassani, said he thought the final document contained "too much religion" and too little protection of womens' rights.

Despite last-minute concessions from the majority Shiites and Kurds, the Sunnis said the document threatened the unity of Iraq and its place in the Arab world.

Ibrahim al-Shammari, spokesman of a leading insurgent group, the Islamic Army in Iraq, said on Al-Jazeera television that the constitution "drafted under the supervision of the occupiers" would divide Iraq and benefit Israel.

Major deal-breaker issues included federalism, Iraq's identity in the Arab world and references to Saddam Hussein's Sunni-dominated Baath Party.

Sunnis fear federalism would lead to the breakup of the country into a Kurdish north and Shiite south, deprive Sunnis of Iraq's vast oil wealth concentrated at the opposite ends of the country, and open the door to Iranian influence in the Shiite south.

Many key Shiite leaders took refuge in Shiite-dominated Iran during Saddam's rule. The constitution identifies Iraq as an Islamic -- but not an Arab -- country, a concession to the Kurds and other non-Arab minorities.

Sunnis also wanted no reference to Saddam's party, fearing that would lead to widespread purges of Sunnis from government jobs and public life.

The parliament speaker, who was not part of the Sunni negotiating team, said the Shiites and Kurds should have been more accommodating to the minority. The Shiite-Kurdish bloc won 221 of the 275 National Assembly seats because many Sunnis boycotted the Jan. 30 election.

"I think to them, they won the election ... so it is an opportunity to them to get whatever they want," al-Hassani told reporters. "If I was in their camp, I would have been more generous."

Although Sunnis account for only 20 percent of Iraq's estimated 27 million people, they still can derail the constitution in the referendum due to a concession made to the Kurds in the 2004 interim constitution. If two-thirds of voters in any three provinces reject the charter, the constitution will be defeated. Sunnis have the majority in at least four provinces.

Defeat of the constitution would force new elections for a parliament that would begin the drafting process from scratch. If the constitution is approved, elections for a fully constitutional parliament will be in December.

Communal tensions have risen since the Shiite-dominated government was announced April 28. Both Shiites and Sunnis accuse the other of assassinating members of the rival sect. Shiites and Kurds dominate the government security services, while most insurgents are believed to be Sunnis.

For the United States, one of the few silver linings in the bitter constitutional debate is that it convinced many Sunnis that they made a profound mistake by boycotting the Jan. 30 election and should take part in the political process.

So few Sunnis were elected that their constitution negotiators had to be appointed, reducing their influence on the committee. Al-Mutlaq called for an extension of Thursday's registration deadline so more Sunnis could participate.

Sunni clerics, who were at the forefront of the boycott campaign, are now urging their followers to register for the referendum and the December national election -- although against the constitution.

The radical Shiite cleric Muqtada al-Sadr, who has considerable influence, has broken with other Shiites and spoken out against the constitution. Al-Sadr has been making overtures to hard-line Sunni clerics in a common front against the draft and the U.S. presence here.

The document included some relatively minor amendments that the Shiites offered after Bush urged compromise.

They included striking the word "party" from the phrase "Saddam's Baath Party," which could enable a future Baath Party to emerge, and letting a future parliament work out rules for implementing federalism.

Sheik Humam Hammoudi, a Shiite and chairman of the drafting committee, said 5 million copies of the constitution will be circulated nationwide in food allotments each Iraqi family receives monthly from the government. Unlike the January elections, Iraqis will not be allowed to vote outside the country because of the difficulty in applying the three-province veto.