Six U.S. soldiers died in roadside bombings and a shooting, the military said Sunday, as lawmakers rushed to persuade Sunni Arabs (search) to accept federalism provisions in the draft constitution that is due in one day.

With intense negotiations continuing just hours before parliament was to ratify the charter, one Shiite legislator, Jawad al-Maliki (search), told The Associated Press that the deadline might have to be extended.

"If we don't reach an agreement today, we might amend the interim constitution and extend the deadline by a minimum of two weeks," he said.

However, U.S. Ambassador Zalmay Khalilzad said the document was on track to be finished on time.

"The Iraqis tell me that they can finish it and they will finish it tomorrow," said Khalilzad in a televised interview." "There are options, obviously, should they need it, but at this point, my information is — and I've just come from a meeting with the Iraqi leaders — that they intend to finish it tomorrow."

Amendments to the country's current charter can be made only with the approval of three-fourths of parliament and unanimous approval of the president and his two deputies. Parliament announced that their next meeting would be Monday at 6 p.m. local time (10 a.m. EDT).

Elsewhere, the U.S. military said three soldiers were killed and one other wounded in a roadside bombing late Saturday near Tuz Khormato, 95 miles north of Baghdad.

One soldier on a patrol was killed Sunday and three others wounded in a blast east of Rutbah, 250 miles west of Baghdad, the military said. In another roadside bombing, one soldier was killed Saturday and another wounded in western Baghdad.

On Friday a U.S. commander said the number of roadside bomb attacks against American convoys in Iraq had doubled in the past year to about 30 per week. Dozens of bombings, usually detonated by remote control, target U.S. and Iraqi patrols each day.

The military said in a brief statement from Baghdad that one soldier was found dead Friday of a gunshot wound. The military said an investigation was underway and did not say where the soldier was found or if an attack was suspected in the soldier's death.

The beheaded body of an unidentified woman was found in the violent southern neighborhood of Dora, police 1st Lt. Thaer Mahmoud said. Two bodies, including one that was beheaded, were found in eastern Mosul, 225 miles northwest of Baghdad, police and hospital officials said.

A roadside bomb along a highway killed one civilian Sunday and injured another in Mahmoudiya, about 20 miles south of Baghdad, police Capt. Saad al-Samaraei said.

Shootings, a mortar attack and a bombing also wounded another 10 people across the capital, police said, and a senior Iraqi Central Bank official, Haseeb Kadum, was kidnapped outside his home.

Elsewhere, a police officer was killed and two others injured in a drive-by shooting in Kirkuk, 180 miles north of Baghdad, police Col. Farhad Talabani said. Gunmen also killed one border guard and injured three others near the northeast town of Khanaqin close to the Iranian border, police said.

Also in Khanaqin, over one thousand Kurds marched to demand that several northern cities such as Sinjar and Kirkuk be included in an autonomous Kurdish region in the north.

In Baghdad, leaders from Iraq's three major groups tried to resolve contentious issues in the constitution such as federalism, but a top Sunni official said his group would never accept terms that they fear will lead to the division of the country.

Other issues, such as the role of Islam in the government and the distribution of wealth, were also on the table.

A meeting of Iraqi leaders took place Sunday between President Jalal Talabani, Kurdish leader Massoud Barzani, former Prime Minister Ayad Allawi and parliament Speaker Hajim al-Hassani, according to Kurdish legislator Mahmoud Othman said.

Othman said another planned session between Sunni politicians and Barzani was scheduled Sunday. Kurdish and Shiite leaders were to meet at the office of Prime Minister Ibrahim al-Jaafari in the evening.

A parliament session scheduled for Sunday was postponed because many legislators were working on the constitution, said Aref Tayfour, the deputy speaker of the assembly.

Talabani predicted Saturday that a draft constitution would be ready by the deadline, and a Kurdish official said the draft would be presented to parliament with or without Sunni approval. Sunni leaders said they were not bound by agreements reached by Shiite and Kurdish leaders.

"We will not be subdued and will continue to cling to our stance," Sunni negotiator Kamal Hamdoun said Saturday. "We don't accept federalism ... We don't want federalism. We are confident that federalism means division and federalism cannot be approved at this time."

However, Othman cautioned Saturday that "if the Sunnis refuse to accept the agreements, we will present the draft as it is to the National Assembly."

That strategy could backfire, however, in the Oct. 15 referendum when voters will be asked to ratify the constitution. According to the country's interim charter, the constitution will be void if it is rejected by two-thirds of voters in three of the 18 provinces. Sunni Arabs are a majority in four.

The U.S. considers the charter a key part of the process to curb a Sunni-dominated insurgency. In his weekly radio address, U.S. President George W. Bush said that the Iraqi constitution "is a critical step on the path to Iraqi self-reliance."

Negotiations were thrown into a tailspin Thursday when the leader of the biggest Shiite party, Abdul-Aziz al-Hakim, called for a Shiite autonomous government in central and southern Iraq, including the southern oil fields. The demand was immediately rejected by Sunni Arab delegates.