BAGHDAD, Iraq, Aug. 13 - The United States ratcheted up its pressure Saturday on Iraqi negotiators who are trying to meet a deadline for writing a draft constitution set for Monday.
Speaking by cellphone from a meeting with Zalmay Khalilzad, the American ambassador to Iraq, a Sunni Arab member of the Iraqi constitutional committee compared the document to a meal that had not finished cooking. "We are still in the kitchen now, but there is nothing yet," said the Sunni member, Haseeb Aref. "There are only pressures on us."
Mr. Aref then apologized and said that because of the meeting with the ambassador he did not have time to say anything else. But a Kurdish member of the committee, Mahmoud Othman, also acknowledged the American pressures and said that there had been constant meetings involving Mr. Khalilzad and many Iraqi officials, including the president, the speaker of the National Assembly and the president of Iraqi Kurdistan.
"Without any doubt, there is American pressure on everybody," Mr. Othman said. "The U.S. wants to reach a solution and finalize an agreement, and they say that the date of Aug. 15 is sacred."
The Americans have repeatedly made it clear that they would consider the constitution a tangible sign of progress in Iraq.
In a reflection of the ethnic tensions that have slowed the negotiations, Mr. Othman contended that "the main problem is with the Sunni Arabs" who he said do not fully accept the notion of federalism - the idea that power should devolve to provincial governments, with the central government in Baghdad exercising overall control.
With the strength of that central control still to be determined, the Sunnis have expressed fears that enshrining federalism in the Iraqi constitution could lead to the dissolution of the country. Other groups have called those fears overblown, particularly the Kurds, who have effectively ruled as an autonomous region in the north since the 1991 Persian Gulf war.
As the constitutional committee pressed to reach its deadline, attacks by insurgents continued around Baghdad. A roadside bomb exploded as an American military convoy passed in Sadr City, a Shiite slum, at 4 p.m. on Saturday, killing at least one Iraqi civilian, an Interior Ministry official said.
No report on the incident was immediately available from the military, but an American Humvee was seen burning at the scene.
Earlier in the day, a suicide car bomber attacked an American convoy in the Dawra neighborhood, an insurgent stronghold in southern Bagh dad, the official said.
The Dawra attack, which killed one Iraqi civilian and wounded another, occurred as American soldiers were defusing a separate roadside bomb. Insurgents have become increasingly sophisticated in carrying out "coordinated" strikes, in which either a decoy or an initial attack is followed by a second wave once American or Iraqi security forces have responded.
Possibly in an illustration of how much United States forces now fear such attacks, Iraqis said that an American military patrol opened fire after a bomb exploded next to its convoy west of Baghdad on Friday, Reuters reported. Fifteen Iraqis were killed and 17 wounded in the incident, the news agency said.
Whether the explosion was followed by insurgent gunfire is unclear, but Reuters quoted an American military official as saying that United States forces "were certainly not involved in any indiscriminate fire incident."
Insurgents also attacked a car carrying a father and his son who work at the Dawra Refinery in Baghdad, one of the largest in the country; the son was killed and the father was wounded, the official said. In an attack in eastern Baghdad, in the Ofali district, a roadside bomb exploded next to an Iraqi Army patrol, wounding five soldiers.
The American military in the northern city of Mosul reported on Saturday that its forces had raided a suspected "clandestine chemical production facility" on Aug. 9. Tests were still being conducted to determine the purpose of the site.
"We don't want to speculate on any possibilities until our analysis is complete," said Col. Henry Franke, identified in a military statement as a nuclear, biological and chemical defense officer.
In the constitution talks, Mr. Othman, the Kurdish member of the committee, said some new agreements had been struck a day after negotiators had settled on a deal to distribute the country's oil wealth. For example, Mr. Othman said, the negotiators had agreed to set a timetable on the return of Kurds to northern cities like Kirkuk from which they had been pushed out as part of Saddam Hussein's program to increase the Arab population there.