Tucson, Arizona | Published: 02.20.2006

BAGHDAD Iraqi political parties have run into major obstacles in talks on a new national unity government, officials said Sunday, raising the possibility of a major delay that could set back U.S. hopes for a significant reduction in troop levels this year.

U.S. officials hope a new government that includes representatives of all Iraq's religious and ethnic communities can help calm violence by luring the Sunni Arab minority away from the Sunni-dominated insurgency so that U.S. and other foreign troops can begin to head home.

But prospects for a broad-based coalition taking power soon appeared in doubt after officials from the Shiite and Kurdish blocs told The Associated Press that talks between the two groups had revealed major policy differences.

The political parties have decided to negotiate a program for the new government before dividing up Cabinet posts - a step that itself is also bound to prove contentious and time-consuming.

Leaders from Iraq's Shiite majority oppose a Kurdish proposal to set up a council to oversee government operations, the officials said. Shiites also reject a Kurdish proposal for major government decisions to be made by consensus among the major parties rather than a majority vote in the Cabinet.

"If the position of the Shiite alliance is final, then things will be more complicated and the formation of the government might face delays," Kurdish negotiator Mahmoud Othman said.

Shiites believe the Kurdish proposals would dilute the power that Shiites feel they earned by winning the biggest number of seats in Dec. 15 parliamentary elections. But while Shiite parties control 130 of the 275 seats, that is not enough to govern without partners.

"Some parties are trying to undermine efforts to form a new government," Shiite politician Ammar Toamah said. "These blocs should not necessarily participate in government."

He also said the Kurdish coalition, which controls 53 seats, was pushing for a role for a secular group led by former Prime Minister Ayad Allawi, a Shiite whose party won 25 seats.

Forming a new governing coalition is crucial to the U.S. strategy for drawing down its forces in Iraq.

Under the new constitution, the new government is supposed to be complete by mid-May, but some U.S. officials believe the process could take longer.

In Nibaie, meanwhile, about 35 miles north of the capital, gunmen ambushed a convoy of trucks carrying construction material to the U.S. military on Sunday, killing four Iraqi drivers. A police general also died in a roadside bombing in northern Iraq.

In Baghdad, a car bomb exploded Sunday afternoon near a Shiite political office in the Jadiriyah district, killing two people, including a policeman, and wounding five, three of them police, officials said.

Minutes later, a suicide bomber detonated explosives strapped to his body at an Iraqi army checkpoint protecting the Defense Ministry in central Baghdad. Three civilians were injured, police said.