Baghdad ? Baghdad shook with bombings and political upheaval Wednesday as the largest Sunni Arab bloc quit the government and a suicide attacker blew up his fuel tanker in one of several attacks that claimed 142 lives nationwide.

The Iraqi Accordance Front’s withdrawal from the Cabinet leaves only two Sunnis in the 40-member body, undermining Prime Minister Nouri al-Maliki’s efforts to pull together rival factions and pass reconciliation laws the U.S. considers benchmarks that could lead to sectarian reconciliation.

The U.S. military announced the deaths of four more American soldiers, including three killed Tuesday in Baghdad by a powerful armor-piercing bomb. The U.S. says these types of bombs are sent from Iran.

Altogether at least 142 Iraqis were killed or found dead, including 70 in three bombings Wednesday in Baghdad. The violence came after July ended as the second-deadliest month for Iraqis so far this year, but with the lowest U.S. death toll in eight months.

Washington has been pushing al-Maliki’s government to pass key laws – among them, measures to share national oil revenues and incorporate some ousted Baathists into mainstream politics. But the Sunni ministers’ resignation from the Cabinet – not the parliament – foreshadowed even greater difficulty in building consensus when lawmakers return after a monthlong summer recess.

President Bush prodded al-Maliki to unite rival factions and show some overdue political progress, the White House said. The two leaders spoke for 45 minutes in a secure video conference.