BAGHDAD, Iraq, July 19 - Two Sunni Arabs involved in drafting Iraq's constitution were assassinated Tuesday afternoon on a busy street in central Baghdad, delivering a setback to the country's fledgling democratic process.
The two men, Mejbil al-Sheik Isa and Damin al-Obeidi, were in a car that was taking them from a meeting of committee members when they were attacked, the officials said. A bodyguard, Aziz Ebrahim, was also killed.
Mr. Isa was among the 15 Sunni Arabs recently appointed as committee members, and Mr. Obeidi was one of 10 newly appointed Sunni consultants. The expansion of the committee was part of an effort by the Shiite and Kurd-dominated National Assembly, under pressure from the Bush administration, to draw more Sunni Arabs into the charter-writing process, both to help cement the country's nascent democracy and to undermine the insurgency by making the process more inclusive.
But the killings raised concerns on Tuesday that those efforts could be jeopardized, and there was disagreement among several Sunni committee members about whether they would suspend their participation pending the outcome of a government investigation of the slayings.
One Sunni member of the committee, who requested anonymity because of concerns about his safety, insisted that the Sunni delegation would not be intimidated into withdrawing from the constitution-writing project. "We need to discuss our reaction to what happened, but I can tell you that we will continue working in the constitution committee," he said.
Attacks aimed at the committee had been widely feared; insurgents had threatened to kill any Sunni Arabs who took part in writing the constitution. Mr. Isa and Mr. Obeidi were the first members to be killed.
Initial suspicion for their deaths fell on Al Qaeda in Mesopotamia, a militant group operating in Iraq and led by Abu Musab al-Zarqawi, who has vowed to overthrow the current government. But by late Tuesday, no group had claimed responsibility.
"There was a threat made by Al Qaeda," said Ayad al-Samaraai, a Sunni member of the committee and a member of the moderate Iraqi Islamic Party. "But I still think that we should wait until we see the results of the investigation."
Ali Muhammad, 17, a guard at the popular Azaem restaurant in the Karada neighborhood, said he was standing outside the restaurant when he saw a minibus pull abreast of the sedan carrying Mr. Isa, Mr. Obeidi and the bodyguard. Three gunmen inside the minibus riddled the sedan with gunfire from AK-47 semiautomatic assault rifles, then escaped in their vehicle down a nearby alley.
Fakhri al-Qaisi, a member of the National Dialogue Committee, a Sunni political organization, said the Sunni members of the constitution-writing committee had repeatedly asked the government to help provide security for them but their requests had not been granted.
"We asked many times about guards, but we did not get any," he recalled. "We are neglected, and no one cares about us. I do not know how we are going to build a country in such circumstances."
The bodyguard who was traveling with the two men on Tuesday was a private guard hired by one of them and had not been assigned by the government, according to the Sunni committee member who requested anonymity. Calls seeking comment from Interior Minister Bayan Jabr or his spokesmen were not returned.
Condemnation of the assassinations was swift and cut across political lines, with Sunni Arabs and Shiites alike criticizing the attack.
"This is the hand of terrorism, which does not want the country to move toward stability and to write the constitution in harmony with all Iraqis," Ali al-Dabagh, a Shiite member of the National Assembly, said in a telephone interview. The slain Sunni Arabs, he said, represented hope for what he called "a middle solution."
The government of Prime Minister Ibrahim al-Jaafari issued a statement saying, "The government promises everyone that it will punish those killers and will continue supporting and encouraging a wide and comprehensive participation of all parties in drafting the constitution."
At the United Nations, Secretary General Kofi Annan reacted to the news "with shock and dismay" and said he hoped the committee would not be deterred "from completing its important task on time," according to his spokesman.
The attacks followed a morning news conference in which Iraq's president, Jalal Talabani, predicted that the constitution could be completed by the end of the month.
Parliament has until Aug. 15 to adopt a draft, though the government has the option of delaying for up to six months. If the deadline is met, the draft will be put to a national referendum by mid-October and elections for a full five-year government would happen in mid-December.
Mr. Talabani reported that the committee had been making good progress, but added that "there are some Arab brothers" who "have some reservations that are being taken into consideration."
"If we can reach an agreement with them," Reuters quoted him as saying, "I believe the constitution can be ready by the end of the month." He did not identify the critics in question, but heavily contested issues include federalism and the role of Islam in Iraqi law.
There was scattered violence around Iraq on Tuesday, killing more than a dozen people.
The most deadly attack occurred about 8 a.m. when insurgents in two cars opened fire on a minibus carrying Iraqi workers to an American military base in Khalis, about 40 miles north of Baghdad. Ten of the workers were killed and the minibus driver was wounded, said an official at the Interior Ministry. The minibus crashed into a passing car, the official said, killing three more people.
A spokesman for the American command confirmed the attack but offered no further details. In an Internet posting later in the day, Al Qaeda in Mesopotamia claimed responsibility and accused the victims of "supporting the crusaders."
Iraqi civilian workers on American military bases in Iraq do not live on the bases and commute from their homes. They hold a wide range of jobs, including interpreting and translating, clerical work and carpentry, sewing and cleaning.
The American command announced Tuesday that an American solider had died in a noncombat-related incident at Camp Arifjan, an American base south of Kuwait City. While the United States maintains a permanent troop presence in Kuwait, the military also uses the country as a staging point for units moving in and out of Iraq.
In Kirkuk, two people, including at least one police officer, were killed in a roadside bomb attack, and five others were wounded, including two police officers, the authorities said.
A member of the city council of Buhruz, near Baquba, was assassinated on the town's main street, said an official at the Baquba police station.
And in Qahira, a neighborhood in Baghdad, three police officers traveling in a police pickup truck survived an assassination attempt but were badly wounded, an Interior Ministry official reported.
Notably, however, there were no suicide bombings for the second day in a row, according to government officials. Suicide bombs became a brutal and defining feature of the landscape during an eight-day stretch from July 10-17. During that period, Greater Baghdad was bloodied by numerous suicide attacks, including an attack on American troops that killed more than two dozen civilians, most of them children, and a suicide bombing on Saturday involving a fuel tanker that killed at least 71 people, most of them civilians, and wounded at least 156.
Mr. Zarqawi's insurgent group, Al Qaeda in Mesopotamia, posted statement on the Internet on Tuesday accusing the American television news media and two Middle Eastern cable news channels, Al Jazeera and Al Arabiya, of trying to "blacken the truth" by underreporting casualties among the American-backed coalition troops, according to the SITE Institute, a monitoring organization in Washington that analyzes postings by Islamic terrorist groups.
In the statement, according to SITE, Al Qaeda in Mesopotamia said that only its information department was free from the "crusader's whip" that drives the foreign media to lie.