New Iraqi Unity Coalition Imperils Shiites' Prime Minister Pick

But he added that "the whole power balance has changed."

Among the changes, the diplomat noted, is the diminished power of the Shiite alliance since elections in January 2005. Sunni Arabs, who largely boycotted those elections, made a strong showing in the December vote.

At least two major roadblocks stand in the way of assembling a coalition that could produce enough votes to challenge Jafari.

The first is the old antipathy between the Sunni Arabs and the Kurds, who bitterly remember the oppression suffered under Hussein's Sunni-dominated dictatorship. The second is that any coalition capable of amassing the two-thirds majority necessary to have a viable candidate for prime minister would need to include at least some Shiite parties.

Saleh Mutlak, head of the Iraqi National Dialogue Front, a Sunni Arab group, said he and others were attempting to woo the Fadhila Party, a smaller party within the United Iraqi Alliance, and other independent members of the Shiite coalition.

"I don't think that we should make it as a fact that the prime minister should be Shiite," Mutlak said. "We are thinking of bringing somebody who has really nationalist, Iraqi tendencies," such as Ayad Allawi, a secular Shiite who earned a reputation for toughness as Jafari's predecessor.

The one danger, Mutlak acknowledged, is that the Shiite parties would refuse to accept political defeat and would mobilize their militias for civil war. Sadr, for instance, has a large militia that waged two sustained uprisings against U.S. and Iraqi forces when Allawi was interim prime minister

"This time I think we have to take the risk and be brave enough to face the situation," Mutlak said. "Unless we do it, Iraq is going to die."