Iraqi Shiite Muslim leaders said early Sunday that they were ending negotiations on the country's constitution after months of increasingly divisive talks and planned to put the draft before the National Assembly later in the day, senior officials involved in the talks said.

Despite some compromises made by Shiites at the urging of the Bush administration, the draft appears not to have won the support of at least some of the negotiators representing Iraq's Sunni Arab minority.

"The chances of bringing Sunni Arabs to the political process are almost lost," said Salih Mutlak, the most vocal and most publicly unyielding of the Sunnis involved in talks on the constitution. "The Sunni Arabs will suffer a lot, unfortunately. Everybody in Iraq is going to suffer from this."

Shiite leaders have said they expect the Shiite- and Kurdish-controlled National Assembly to rubber-stamp the draft. Assembly approval would send it to a national vote, which must be held by Oct. 15.

If the constitution passes the referendum, a new, full-term assembly would be elected by Dec. 15. But if voters reject it, the December election would be for an assembly that would serve just one year and would try again to frame an acceptable constitution -- a process that, with Iraq's already inflamed sectarian and ethnic tensions, would put great stress on the country's fragile government-building effort.

The constitutional talks have played out as rifts grow within Iraqi society. After heavy fighting between rival Shiite militias last week subsided in the south, Sunni tribes battled Saturday in the west and north, Sunni tribal leaders and others said.

In Qaim, near the Syrian border, at least 35 people were killed in mortar, rocket and small-arms battles between a local tribe allied with Abu Musab Zarqawi's insurgent group, which has vowed to kill anyone who takes part in elections, and a rival tribe that has worked with the local government, said tribal leaders and hospital officials.

In Dawr, another mostly Sunni city north of Baghdad, bombers blew up a mosque that the Iraqi Islamic Party was using as headquarters and badly damaged a school serving as a voter-registration center, party and school officials said.

Throughout the constitutional negotiations, the toughest issue remained federalism, which Sunnis and many Shiites say would allow the oil-rich, heavily Shiite south to form a separate federal region like the already autonomous Kurdish north. In a key compromise, Shiites decided to leave the creation of any new federal region other than Kurdistan to the next National Assembly, officials said.

That was the concession pushed by President Bush in a phone call last week to Abdul Aziz Hakim, the head of a leading Shiite religious party in Iraq's coalition government, one official familiar with the talks said.

Bush's call indicated strong U.S. pressure on Shiites to make compromises in hopes of winning Sunni support for the constitution and defusing the country's Sunni-led insurgency.

"I told them we found it absolutely necessary for the benefit of Iraq as well as we who are involved here now, the American blood and treasure being engaged now, that they make the effort to get the Sunni buy-in," U.S. Ambassador Zalmay Khalilzad said. "We view the constitution as a national compact and view the Sunni buy-in as important not only for the constitution to work as a common road map for the country for the future . . . [but] as a military necessity -- we want to separate the population from extremists and insurgents."

Other sides had asked the "Sunnis to give their bottom lines," Khalilzad said. Sunni negotiators made clear their bottom line was federalism, which most Sunnis oppose as a mechanism that could lead to the breakup of Iraq. "They could not support a constitution that made it automatic that any region could form a federal region" beyond the Kurdish north, Khalilzad said.

Hakim, leader of the Supreme Council for the Islamic Revolution in Iraq, this month proposed creation of what would be an oil-rich Shiite sub-state in the south, comprising nine of Iraq's 18 regions. Sunnis and others have voiced fears that such a state would be under the sway of the Shiite theocracy in neighboring Iran, while leaving Sunnis in central and western Iraq with few resources and little political power.

The draft constitution, as it stood early Sunday, allowed for the next National Assembly to approve creation of a new federal region by a simple majority, authorities said. Shiites make up an estimated 60 percent of Iraq's population and would almost certainly hold a majority in the next assembly.

Sunni Arabs, who made up Iraq's ruling elite for decades but fell from dominance with the toppling of Saddam Hussein in 2003, largely stayed out of this past January's National Assembly elections in response to insurgent threats and boycott calls from Sunni leaders. The move left them with comparatively little political leverage in the constitutional negotiations.

The constitutional draft discussed by leaders early Sunday appeared not to have changed greatly on its main points from a proposal submitted Friday by Shiite leaders, who described it then as their last, best offer. It omitted reference to the Shiites as the majority in Iraq and cut a reference to Shiite spiritual leaders being entitled to special reverence, according to officials.

In a compromise sought by Sunnis, the draft requires only a vote of an absolute majority to dissolve the government committee created to purge high-ranking, criminal or disloyal members of Hussein's Baath Party from government positions, officials said. The draft also removes a specific condemnation of Baathists, officials said.

Some Sunni leaders responded Saturday to the Shiites' proposal with 13 objections, and later with their own counterproposals.

Mishan Jabouri, a National Assembly member who found the Shiite offer on federalism unacceptable, said he had hoped a counterproposal would find acceptance and that hard-liners among his own people would yield.

"I appealed to them because . . . we have a historic chance ahead of us," Jabouri said. "I told them, 'I fear for the country from you. I am about to cry, because you are leading the Sunni street.' "

Khalilzad spoke to the top Sunni negotiators Saturday afternoon "and we said we don't agree," said Mutlak, the Sunni negotiator. "He said this is as far as he can go. We gave him two pages of demands, and he said he can't go anymore."

"None of the demands are met," Mutlak said. "There's no agreement and they will submit it . . . . Things will deteriorate in every aspect. The stability will be less. The violence will be up. The demonstrations on the street will be up."

"They informed us to come tomorrow at 3 o'clock to celebrate," Mutlak said. Asked if he felt like celebrating, Mutlak responded, "What do you think?"

About 350 Sunnis rallied near Kirkuk, in northern Iraq, on Saturday against the proposed constitution, chanting anti-federalism slogans. Past days' rallies in other cities saw angry Sunnis waving posters of Hussein.

The U.S. military, meanwhile, released 1,000 detainees from Abu Ghraib prison Saturday in response to an Iraqi government request to speed up the process of reviewing individual cases, said Lt. Col. Guy Rudisill, a U.S. military spokesman on detainees. The release leaves 3,800 prisoners in the U.S. section of Abu Ghraib, which the Americans plan to turn over to the Iraqi government next year, Rudisill said.

U.S. military forces said in a statement that troops in Mosul on Thursday killed a Saudi, identified only as Abu Khallad, who had worked with recruiters in Saudi Arabia to bring foreign fighters into northern Iraq.

In political violence on Saturday, an explosion inside a house where insurgents allegedly were preparing bombs killed one man near Kirkuk, police Col. Yadgar Abdullah said. Gunmen killed an Iraqi deputy battalion commander, Lt. Col. Muhammad Fakhri, at Kirkuk on Saturday, police said.

U.S. forces at Hamrin mountain, 40 miles south of Kirkuk, arrested four Iraqi policemen after an explosion targeting an American military convoy, police Capt. Ahmad Sabawi said.

Special correspondents Naseer Nouri in Baghdad and Salih Saif Aldin in Tikrit contributed to this report.

Iraq's parliament speaker, Hachim Hasani, sitting directly to the right of the flag, holds a meeting with Sunni Arab negotiators in his office in Baghdad.Salih Mutlak, a Sunni negotiator, was displeased with the final draft of the Iraqi constitution.