U.S. casualties have been rising since President Bush ordered nearly 30,000 more troops to Iraq in a major push to pacify Baghdad and surrounding areas. The goal was to curb the violence so Iraq's Shiite, Sunni and Kurdish leaders can strike agreements to share power in this fractious country.

But progress toward agreements to share oil wealth, provide a greater political role to the Sunni minority and shore up local governments has been slow because of deep suspicions after four years of bloodshed.

In a hopeful sign, radical Shiite cleric Muqtada al-Sadr called off a July 5 march to a bombed shrine in Samarra north of Baghdad after appeals from the government, which feared Sunni extremists would attack marchers along the way.

Sheik Asad Al-Nassiri, an aide to the cleric, told a congregation at Friday prayer services in Kufa that al-Sadr canceled the march because of "the government's inability to secure the route and many officials' appeals for a postponement."

At the same time, however, anger has been welling up among Sunni Arabs, who complain they are being marginalized in the Shiite-dominated government.

A Sunni political party said Friday that four Sunni Cabinet members will refuse to attend government meetings to protest the way Prime Minister Nouri al-Maliki handled legal proceedings against the fifth Sunni minister.

Earlier this week, an arrest warrant was issued for Culture Minister Asad Kamal al-Hashimi and security forces raided his Baghdad home after allegations he masterminded an assassination attempt against a politician two years ago.

Sunni politicians considered the move politically motivated and asked al-Maliki, a Shiite, to do something to stop it. The prime minister refused, saying he would not intervene in the work of the judiciary.

"The ministers have decided to suspend their participation in government meetings because they consider the stance of the prime minister and the government unsuitable," Ayad al-Samarraie, a leading member of the Sunni bloc the Iraqi Accordance Front, told AP.

"Had this minister been a member of his (al-Maliki's) party, would he have dealt with the matter the way he did?" al-Samarraie asked.

Muhannad al-Issawi, a spokesman for Accordance Front leader Adnan al-Dulaimi, said the boycott of the 37-member Cabinet "will continue until a compromise is reached."

Al-Issawi said the Sunnis were also protesting the dismissal this month of the Sunni speaker of parliament, who was voted out by the legislators because of erratic behavior.

In April, six Cabinet ministers loyal to al-Sadr quit the government to protest his refusal to call for a timetable for American troops to leave. They have not been replaced.