BAGHDAD, Iraq -- A suicide car bomber struck a U.S. convoy waiting at an intersection yesterday in Baghdad, killing seven people -- including one U.S. soldier -- and wounding more than 90. More than a dozen others died in scattered attacks across the capital.

Also, a U.S. Marine assigned to the 2nd Marine Division was killed Monday by small-arms fire in Ramadi, 70 miles west of Baghdad, the U.S. military said. The deaths brought the number of U.S. service members killed in Iraq this month to at least 32.

Violence raged as Iraqi political leaders showed little sign of compromise less than a week before a deadline for approving a new constitution. Faction leaders conferred for about four hours last night, hoping to overcome their differences and produce a charter by Monday.

Participants said the talks focused on Kurdish demands for a federal state, and although some progress was made, there was no final agreement on the issue. More talks were set for today.

The U.S. convoy was stopped at a busy intersection when a driver detonated a vehicle packed with explosives, the U.S. Army said. Six Iraqi civilians also were killed; scores of Iraqis and two U.S. soldiers were wounded.

At least 1,836 members of the U.S. military have died since the Iraq war started in March 2003, according to an Associated Press count.

The United States hopes that progress on the political front, including adoption of a democratic constitution, will help deflate the Sunni Arab-led rebellion and enable the U.S. military and their partners to begin withdrawing troops next year.

"It's important that they stay with their timetable" on the constitution, Defense Secretary Donald H. Rumsfeld said yesterday. "This will be a critical step in persuading the majority of the Iraqis that the new Iraq is worth fighting for, that they have a stake in it."

Rumsfeld told Pentagon reporters that the constitution "could well turn out to be one of the most powerful weapons to be deployed against the terrorists," and the insurgents are "determined to stop the constitutional process through terror and intimidation."

Late yesterday, representatives of political factions met for a second round of talks aimed at breaking the deadlock over the constitution, which the parliament must approve by next Monday. Talks were postponed Monday by a severe sandstorm.

The constitution also needs approval from voters in an Oct. 15 referendum. Passage would lead to elections in mid-December.

At the beginning of yesterday's meeting, presidential spokesman Kamran Qaradaghi told reporters that the latest talks would focus on federalism, distribution of wealth and the elections law.

Kurds demand that Iraq be transformed into a federal state, so they can continue to run their autonomous mini-state in the north. Sunni Arabs oppose federalism because they fear that the Kurds want to secede and dismember Iraq.

Kurdish leader Massoud Barzani joined the talks yesterday. Barzani, who was stranded in northern Iraq by the sandstorms, has vowed not to compromise on federalism.

A prominent Sunni Arab on the constitutional committee, Saleh al-Mutlaq, suggested that federalism could be decided by the parliament to be elected in December. "We will not accept federalism in these circumstances," al-Mutlaq told The Associated Press. He warned that if Kurdish demands are accepted, "they will have grave consequences" for the future of Iraq. He did not elaborate.