BAGHDAD, Iraq — Political groups representing Iraq's minority Sunni Arabs called yesterday for new delays in approving a national constit-

ution, complaining that they had been cut out of final-hour negotiations between Shiite Muslims and Kurds and appealing to U.S. and U.N. officials to intervene.

Also yesterday, Chuck Hagel of Nebraska, a leading Republican senator and prospective presidential candidate, said the war in Iraq has destabilized the Middle East and is looking more like the Vietnam conflict from a generation ago. Hagel, who received two Purple Hearts and other military honors for his service in Vietnam, also reiterated his position that the United States needs to develop a strategy to leave Iraq.

Iraq's transitional National Assembly is scheduled to approve a final draft of the country's first democratic constitution today after missing its Aug. 15 deadline, when it voted instead to give itself one more week to seek compromises on key issues.

Shiites and Kurds, both long oppressed during Saddam Hussein's regime by a strong central government dominated by Sunnis, have written a draft that creates a federal system allowing for greater regional autonomy. Sunnis have staunchly opposed building such federalism into the constitution, fearing it will lead to the fracturing of Iraq into separate countries.

"We need more time to negotiate," Sheik Abdel Nasser Janabi, a leading Sunni negotiator, said yesterday. "I see an attempt to exclude the Arab Sunnis."

Sunni Arab negotiators, in a statement, urged the U.S., the United Nations and the international community to intervene to prevent a draft that lacks unanimous agreement among all three factions, saying it "would make the current crisis more complicated."

Shiites and Kurds appeared to be moving toward using their majority in the National Assembly to approve a draft of the constitution over Sunni objections. Although some Shiite negotiators were expressing hope that they would achieve a consensus with Sunnis and meet today's deadline, Sunni leaders complained that they had been invited to only one meeting during the past week.

"The meetings have not been serious ones, and time is running out," Sunni negotiator Saleh Mutlaq said. "We do not want a constitution that is molded in the final moments and then thrust upon us to sign."

In response, Sunnis and some disgruntled Shiites are threatening to take the fight to the polls and try to defeat the constitution if it is presented as scheduled to Iraqi voters in an Oct. 15 referendum.

"Everyone is getting ready for a big battle," said Hassan Bazzaz, political-science professor at the University of Baghdad.

A source close to the talks, who asked not to be identified because of the sensitive nature of negotiations, said Shiite and Kurdish representatives had basically abandoned hopes of a three-way deal. The Sunni position, he said, is "directly contrary to what the others want."

Even acting on their own, Kurds and Shiites would need to reach agreement on several difficult issues, chiefly related to how to divide Iraq's oil wealth.

If negotiators do not reach an agreement today, legislators can again approve a delay. The National Assembly will be disbanded, however, if it fails to approve a constitution to put before the voters. New parliamentary elections would be conducted by the end of the year, and the process of writing a charter would start anew — a delay strongly opposed by the Bush administration.

In his remarks yesterday, Hagel, the Nebraska senator, scoffed at the idea that U.S. troops could be in Iraq four years from now at levels above 100,000, a contingency for which the Pentagon is preparing.

"We should start figuring out how we get out of there," Hagel said on "This Week" on ABC. "But with this understanding, we cannot leave a vacuum that further destabilizes the Middle East."

Hagel said "stay the course" is not a policy. "By any standard, when you analyze 2 ½ years in Iraq ... we're not winning," he said.

President Bush was preparing for separate speeches this week to reaffirm his plan to help Iraq train its security forces while its leaders build a democratic government. Saturday, Bush said the fighting there protected Americans at home.

Other developments

• The U.S. military said it has ordered a criminal investigation into the June death of Mohammed al-Sumaidaie, 21, the cousin of Iraq's delegate to the United Nations. The delegate alleged that Marines killed his unarmed relative during a raid in western Iraq.

• A car bomb exploded near a restaurant in a Shiite district of Baghdad, killing four civilians, police said.