With three days remaining before the deadline for Iraqi politicians to complete their draft of a permanent constitution, U.S. Ambassador Zalmay Khalilzad has taken a leading role in negotiations among rival factions, Iraqi lawmakers said Friday.

For at least two days, Khalilzad has huddled in the capital's fortified Green Zone with Kurdish, Sunni Arab and Shiite Arab blocs from the committee writing the document. He presented a written, U.S.-backed approach to unresolved questions such as the role of Islam in determining law and the degree of autonomy to grant regional governments, several committee members said.

The U.S. proposal, according to politicians who have examined it, includes endorsing the principle of regional autonomy, such as that enjoyed by Kurdish-populated provinces in the north, but deferring any decision about creating new regions until after Iraq's next elections, slated for December. Some power would be devolved to provincial governments as a step toward broader federalism.

Khalilzad's more aggressive stance -- which also includes a recent call for lawmakers to enshrine rights for women -- comes as President Bush and others in Washington have made strong statements about the need for the constitution to be completed on time. It stands in contrast to the posture taken earlier this summer by American diplomats here, who played down the U.S. role in what they termed an Iraqi process.

Reached by telephone, a spokesman for the U.S. Embassy declined to comment Friday.

"The Americans say they don't intervene, but they have intervened deep," said Mahmoud Othman, a Kurdish member of the constitution committee who said he met with U.S. officials Thursday and Friday. "They gave us a detailed proposal, almost a full version of a constitution. They try to compromise the different opinions of all the political blocs. The U.S. officials are more interested in the Iraqi constitution than the Iraqis themselves, because they promised their people that it will be done August 15."

Under Iraq's interim constitution, called the Transitional Administrative Law, the new document must be completed by Monday so it can be put to a nationwide referendum on Oct. 15, with new parliamentary elections following two months after that. The process is widely considered a prerequisite to any significant withdrawal of U.S. forces from Iraq next year.

While Iraqi officials have long vowed to complete their work on time, some have recently suggested that might not happen. The task ahead is "not easy," Othman acknowledged.

Committee members are still debating protections for women's rights and the role of Islam in determining Iraqi law, but federalism has emerged as the most significant barrier to a consensus, several politicians said.

Kurds, who already have a regional parliament and large militia, favor broad autonomy for regional states. But minority Sunni Arabs, who largely boycotted Iraq's elections in January, fear that any further extension of a federal system could lead to the dissolution of the country. Meanwhile, Shiite Arabs, who control the government's ruling coalition, appear split on the issue. On Thursday, the leader of a dominant Shiite political party called for the establishment of a Shiite state in central and southern Iraq, but the Shiite-led government denounced the proposal.

Salih Mutlak, a Sunni Arab member of the constitution committee, called the differences among the blocs on federalism and other issues "minor now." He said Sunnis would prefer that, rather than endorsing the principle of federalism, the document should leave "all possibilities open" for future governments to select, "including federalism."

But stronger opposition to the principle was voiced during Friday prayers at Um al-Qura, Baghdad's largest Sunni mosque. Mahmoud Sumaidaie called federalism "a conspiracy to partition the country" and urged Sunnis to be prepared to vote down the document in the referendum if it does not suit their goals.

Jalaladeen Sagheer, the Shiite preacher at the capital's Buratha mosque, focused much of his sermon on the constitution's approach to Islam. Shiites and Sunnis "do not accept to deal with Islam as a neglected item in the constitution," he said.

Outside of the political wrangling, it was a relatively quiet day in Iraq. Two U.S. soldiers were injured when their helicopter crashed near the northern city of Kirkuk, according to a statement from the military.

A soldier was killed Thursday by a roadside bomb near Tikrit, the Army said Friday. An Iraq-based U.S. commander visiting Washington, Army Brig. Gen. Yves J. Fontaine, told reporters at the Pentagon that roadside bomb attacks on convoys here had roughly doubled to 30 a day but that the rate of casualties caused by them had declined.

Special correspondents Naseer Nouri and Khalid Saffar in Baghdad contributed to this report.

Soldiers check an Apache helicopter that crashed Friday in the Kirkuk area, injuring two U.S. service members. U.S. envoy Zalmay Khalilzad is reportedly participating in negotiations among factions.