Assassination has proved itself once again as a powerful political tool. Its latest achievement poses a serious threat to Iraqi efforts to draft a new constitution by an Aug. 15 deadline.

A gunman shot and killed Mijbil Issa, one of the 15 Sunni Arabs appointed to the parliamentary committee named to draft the constitution. He and an adviser were killed in front of a restaurant in Baghdad. Two other Sunni committee members had resigned earlier under death threats. The remaining 12 Sunnis suspended further participation in the drafting committee pending action on their demands for an international investigation of the killings and a still greater role for Sunnis in the drafting of the constitution.

The ambitious schedule adopted after the Jan. 30 Iraqi elections calls for Parliament’s approval of the constitution by Aug. 15, its submission two months later for a referendum, and, if the charter is approved, a new national election in December to create a fully constitutional government and open the way for a possible scaling down of U.S. and other foreign security forces. But, in the referendum, if two-thirds of the voters in three provinces vote “no,” the constitution will be rejected.

Behind the political maneuvering and the gunfire is a struggle over the basic structure of the future Iraqi government. The majority religious sect, the Shiites, as well as the Kurds, tend to favor a decentralized structure. Some Sunnis, the party of Saddam Hussein, are said to fear that a federalist pattern would split the country into Kurdish, Shiite and Sunni enclaves.

The Washington Post quotes the Shiite committee chairman, Humam Hammoudi, as calling the projected new government the “Federal and Islamic Republic of Iraq.” The report said that a Kurdish committee member called it merely the “Federal Republic of Iraq,” adding that “Once you say that a state is Islamic you say that a state should pray, perform the hajj,” referring to the pilgrimage to Mecca.

The Sunnis, believed to be the backbone of the continuing insurgency, with its suicide bombers killing a dozen or more Iraqis almost every day, seem intent on wrecking efforts to create a constitutional government, especially if it gives home rule rights to the more numerous Shiites and Kurds. Some Sunnis seem to dream of a return to the supremacy they enjoyed under Saddam Hussein and the repression of the other two sects.

U.S. officials, who had urged the inclusion of Sunnis in the drafting of the constitution, have been working with the interim government to bring Sunnis into the process and try to wean them away from violence.

The problem is, as recent events demonstrate, that violence works.