Gunmen assassinated a Sunni Arab member of a committee drafting Iraq's constitution Tuesday, another blow to U.S. and Iraqi efforts to draw members of the disaffected community away from the insurgency and into the political process.

Mijbil Issa (search), a committee member, Dhamin Hussein, an adviser to the group, and their bodyguard died in a hail of gunfire from two vehicles as they left a restaurant in Baghdad's Karradah district, police said.

Issa was among 15 Sunni Arabs appointed last month to the 55-member constitutional committee — made up mostly of Shiites and Kurds — to give the Sunni minority a greater voice in building a new Iraq. Ten other Sunnis, including Hussein, were named as advisers to the committee.

Insurgents had threatened Sunnis who help draft the constitution, and two committee members resigned earlier because they feared for their lives. Issa was the first to be assassinated.

Parliament speaker Hajim al-Hasani (search), among the highest-ranking Sunni Arabs in the Iraqi leadership, said the assassination was an attempt "to hinder the political and democratic process in Iraq."

"We confirm our commitment and intention to confront brutal terrorism and build the bright future of our country," al-Hasani said.

The attack came as the committee was meeting at Baghdad's Convention Center in the Green Zone (search). The session was suspended when members learned of the killings.

Washington has urged the government of Prime Minister Ibrahim al-Jaafari (search) to give Sunnis a greater role in political life. Most Sunnis boycotted the Jan. 30 election, handing control of the new parliament to Shiites and Kurds.

It's hoped that including Sunni Arabs in the political process will undermine the Sunni-dominated insurgency, which accelerated attacks after al-Jaafari announced his government April 28. Sunnis enjoyed a privileged position under the rule of Saddam Hussein.

Both Shiite and Sunni politicians condemned the slayings and promised the attack would not stop them from finishing the constitution by the Aug. 15 deadline. The charter is to go before voters in mid-October.

"The assassination will not change anything concerning our participation," Sunni committee member Mohammed Abed-Rabbou said. "Our stance is fixed and those who decide to follow this track expect such things."

Committee Chairman Human Hammoudi said the assassination was intended "to hinder the political process, but we will continue our work, and so will our Sunni brothers."

Ali al-Adeeb, a prominent Shiite from al-Jaafari's Dawa party, blamed "terrorist forces" for trying to undermine democracy in Iraq, but said Sunnis on the committee "have the courage to continue their work."

In Jordan, Iraq's planning minister, Barham Salih, told reporters the killings serve as a reminder Iraq's challenges.

"But we believe we should double the efforts for the reconstruction of Iraq and to make sure that the terrorists and extremists would not win," said Salih, a Kurd who was attending a conference on Iraqi reconstruction.

Earlier Tuesday, President Jalal Talabani (search) predicted the constitution could be completed by the end of July if a deal can be worked out with Sunni Arabs, who have reservations about parts of the document.

Privately, however, several committee members have expressed doubts that differences can be overcome with less than a month to go before the deadline.

Major obstacles include whether to describe Iraq as an Arab country — which the non-Arab Kurds oppose — and federalism, which the Kurds demand but Sunnis fear will lead to the disintegration of Iraq. Some Shiites want a stronger role for Islamic law.

The United States and Britain are putting strong pressure on the committee to meet the Aug. 15 deadline — in part to demonstrate progress at a time when support for the Iraq mission is eroding due to mounting casualties.

"America and England are in a hurry so that a constitution be drafted," complained Kurdish committee member Mahmoud Othman. "We are not in hurry. The deadline is Aug. 15. I say Sept. 15, what is the difference? This is the problem. They are interfering in our affairs."

The insurgents have stepped up bombings and assassinations. On Tuesday, gunmen opened fire on a minibus carrying Iraqi workers to a U.S. air base near Baqouba, killing 13. Police said the dead included 10 base employees and three people in another vehicle.

Gunmen also killed seven people, including a police colonel, in a series of attacks in Mosul, 225 miles northwest of Baghdad.