By John O'Neil

The leader of Iraq's most powerful party indicated today that his group would block substantive changes to the country's new constitution. Last fall, as Sunni Arabs protested vehemently against the proposed constitution, the Shiite and Kurd leaders who dominated its drafting promised that a panel would be created which could recommend amendments during the four months following the formation of a new government.

Amendments would need a majority in Parliament to win approval, and the Sunni parties are certain to hold far fewer seats than that; moreover, the Shiites and Kurds did not bind themselves to lend their support to any specific change. Still, the promise of a chance to seek changes was crucial in gaining support for the constitution from the largest Sunni party, the Iraqi Islamic Party, just before the October referendum.

But Abdul Azziz al-Hakim, the leader of the Supreme Council for Islamic Revolution, the most influential group in the ruling Shiite coalition, appeared to pull back from any suggestion of significant change. "The first principle is not to change the essence of the constitution," he said, during a speech in honor of the Muslim holiday of Eid al-Adha, news agencies reported. "The constitution was endorsed by the Iraqi people."

Mr. Hakim appeared to rule out in particular any change in the constitution's provisions allowing the creation of strong regional provinces, a point that had angered many Sunnis. "It is our responsibility to form Baghdad provinces and southern Iraq provinces," Mr. Hakim said, news agencies reported.

Even after the constitution's endorsement by the Iraqi Islamic Party, Sunnis voted overwhelmingly to reject it, while Kurds and Shiites had equally lopsided tallies in its favor. Sunni leaders have complained that the provisions allowing the creation of strong provinces will lead to the dismemberment of the country, with Kurds and Shiites ruling autonomous areas that contain the vast majority of the nation's oil wealth.

Mr. Hakim also said today that the United Iraqi Alliance, which appears to have won about half of the seats in the new Parliament, would announce its choice for prime minister "in the next few days," according to Reuters. After the voting for a provisional Parliament last year, many weeks of maneuvering preceded the choice of Ibrahim al-Jafaari as prime minister.

Mr. Hakim's speech today followed tough statements he made last week in the wake of suicide bombs that killed more than 200 people over two days. Mr. Hakim criticized the United States and Sunni parties that encouraged the insurgency. Responsibility for the attacks, he said, rested "on the multinational forces and the political powers that declared publicly their support for terrorism. Our people will not be patient for much longer with these dirty sectarian crimes," he said.

Mr. Hakim's criticism of the United States referred to recent pressure from the American forces to rein in the Iraqi security forces, which are under Shiite control. American officials have cited growing evidence that Shiite leaders have carried out a program of torture and assassination against Sunni Arabs. Mr. Hakim's statement on the constitution comes at a delicate time, as negotiations continue over the formation of a government based on last month's parliamentary elections.

Even though final election results have not been posted, the Shiite and Kurdish groups who appear to hold a majority of seats have been negotiating to create a government of national unity, including Sunni politicians and secular Shiites. Many Sunni leaders, as well as secular Shiites, charged after the December vote that there had been widespread fraud, a contention disputed by observers from the United Nations. In his speech today, Mr. Hakim called on Sunni politicians to stop complaining about the results and accept the election's outcome.