BAGHDAD, Iraq – In another last minute standoff, Iraqi leaders put off a vote on a draft constitution late yesterday, adjourning Parliament at a midnight deadline in a bid for more time to win over the Sunni Arab minority whose support is key to stopping the insurgency.

The Shiite-Kurdish faction that submitted the draft constitution expressed optimism that a deal was still possible within a few days. But top Sunni Arab leaders said flatly that compromise was far off. More than 20 issues still divide the sides, one of four top Sunni Arab negotiators, Saleh al-Mutlaq, said. Those issues include federalism, power-sharing, and how the constitution should speak about Islam.

“This constitution is full of land mines that would explode on Iraqis. This constitution will divide the country,” Mr. al-Mutlaq said.

The American military said two American soldiers from Task Force Liberty were killed yesterday by a roadside bomb during a patrol north of Baghdad, and two more soldiers died when their vehicle overturned during an operation near Tal Afar.

Washington had applied enormous pressure on the Iraqis to meet the original August 15 deadline, but parliament instead had to grant a week’s extension, which they again failed to meet.

The Shiite-Kurdish draft would fundamentally transform Iraq from the highly centralized state of Saddam Hussein into a loose federation of Kurds, Shiites, and Sunni Arabs. The Sunnis oppose that decentralization, fearing it would cut them out of the country’s oil wealth and leave them powerless.

On the issue of Islam, Mr. al-Mutlaq said Sunni Arabs objected to the draft because it called Iraq an Islamic country and not an Islamic and Arab country. The Kurds are mostly Sunni Muslims but they are not Arab.

The Shiite-Kurdish faction finished the draft yesterday and formally submitted it to parliament as the lawmakers convened minutes before a midnight deadline. But the negotiators quickly withdrew the draft because of the fierce Sunni Arab resistance.

The 15 Sunni Arab members of the drafting committee issued a statement early today saying they had rejected the constitution because the government and the committee did not abide by an agreement for consensus.

“We reject the draft constitution that was submitted because we did not have an accord on it,” a Sunni delegate, Nasser al-Janabi, said.

Although the statement was issued after parliament had deferred a decision, it was significant because it indicates the Sunnis may try to block any accord if they do not agree with it entirely. That could severely complicate negotiations in coming days.

One Shiite negotiator cautioned it was “not possible to please everyone.” But the negotiator, Humam Hammoudi, Shiite chairman of the 71-member committee that struggled for weeks to try to complete the draft, said “many things have been achieved in this constitution.”

Parliament speaker Hajim al-Hassani, a Sunni Arab, said there was strong interest in reaching unanimity on the draft “so that the constitution pleases everyone.” He told reporters that the main outstanding issues were federalism, the formation of federal units, problems related to mentioning the Baath Party in the constitution, and the division of powers between the president, the parliament, and the Cabinet.

Lawmakers were able to keep parliament from having to disband by formally submitting the draft by the deadline – although they then withdrew it.