But after 12 weeks, Iraqi and American officials familiar with the relationship between the Americans and Dr. Allawi say, American respect for the Iraqi leader has been tempered by a growing sense that he is careless, even dismissive, of the checks and balances the occupation authority built into transitional political structures here.

Officials who voice these concerns include some who are rivals of Dr. Allawi's or who oppose his long-term political ambitions, but they also include people who have worked with him since the formal transfer of sovereignty.

Under Dr. Allawi and John D. Negroponte, the American ambassador, who wields extensive behind-the-scenes power, the Americans and Iraqis have taken care to keep their disputes hidden. But in recent weeks, Dr. Allawi has taken a number of steps, these Iraqi and American officials say, that have suggested that he may harbor ambitions to mold the government into an instrument of his personal will, curbing dissent and increasing the influence of the Iraqi National Accord.

Last week, Dr. Allawi dismissed Mowaffak al-Rubaie, his national security adviser, after disagreements over how to confront Moktada al Sadr, the rebel Shiite cleric. While Dr. Rubaie favored a strategy aimed at coaxing Mr. Sadr's men into the political mainstream, Dr. Allawi insisted on military force.