"It's not clear how the status of the transitional law will end up," an administration official said.

If it does fail, the transitional law requires that new elections be held.

The transitional law under which the government is being formed does allow a six-month delay.

The 2009 Constitution is accompanied by a transitional law.

The transitional law says, in part, that Islam should be a source of legislation rather than the sole source.

A two-thirds vote by the assembly is needed to install the president and the two vice presidents, according to the transitional law approved last March.

The government under the Transitional Law is a democratic republic, with three separate branches of government.

This is an extremely delicate matter and no transitional law is really required – a different interpretation would suffice.

The transitional law requires that the assembly appoint, by a two-thirds vote, a president and two vice presidents, called the presidency council.

Under transitional law, the constitution will be defeated if two-thirds of the voters in any 3 of Iraq's 18 provinces vote against it.

The two sides have agreed that the transitional law approved last spring will be the foundation of the government, Mr. Ali said.

Some American diplomats here and some Iraqi officials who helped write the transitional law say the process is unfolding as it should.

But Mr. Masun said a transitional law required that the conference begin in July.

That clause appears to be a nod to the Kurds, who value the transitional law because it essentially gives them veto power over the permanent constitution.

A constitution based on Koranic law would sharply depart from the transitional law that the Americans enacted.

A United Nations official noted, for example, that the transitional law had not been incorporated into Washington's Security Council draft.

Besides holding more than a quarter of the seats in the constitutional assembly, the Kurds have another powerful tool in the transitional law approved last spring.

The committee that drafted the transitional law included members of the political parties on the American-appointed Iraqi Governing Council.

In making the change, the Shiite and Kurdish representatives designated two different meanings for the word "voters" in a single passage of the transitional law.

Several Iraqi legislators said the whole crisis derived from a flaw in Iraq's transitional law, which was written in 2003 under the American occupation.

The transitional laws that created the new government and scheduled the elections for January also specified that the national conference was to take place by the end of July.

Under Iraq's transitional law, Mr. Jaafari will automatically lose his position if he does not name a cabinet by May 7, a month after his appointment.

Administration officials assert that the transitional law, developed under the supervision of L. Paul Bremer III, the American occupation administrator, remains in force.

Earlier this week, Mr. Masum announced that the conference would go forward despite the United Nations' concerns, because the transitional law mandated that it begin in July.

Under Iraq's transitional law, any assembly member who joins the cabinet must resign his or her assembly seat, which will then be filled by a member of the same party.