Baghdad, Iraq ? A suicide bomber wearing a police uniform blew up his car at police headquarters in Tikrit, killing at least 15 people in Saddam Hussein’s hometown in the bloodiest of several attacks Thursday that claimed 30 lives. Two American soldiers were among the dead.

The suicide bombings and other attacks came as politicians negotiated behind the scenes to forge the alliances needed to win enough backing in the 275-seat National Assembly for the post of prime minister.

The U.S. command said two American soldiers were killed and two wounded in separate bomb attacks, one northeast of Baghdad in Qaryat and a second near Samarra, west of Qaryat.

U.S. Marines and Iraqi troops, meanwhile, pressed a joint operation to root out insurgents in parts of the so-called Sunni triangle. The military said it detained 17 suspected insurgents and seized several weapons caches.

Politicians of all stripes sought out representatives of Iraq’s Sunni minority, whose support they need to isolate the insurgency.

Many insurgents are thought to be loyalists of Saddam’s outlawed Sunni-dominated Baath Party.

A powerful Sunni organization believed to have ties with the insurgents, the Association of Muslim Scholars, rejected any role in the government — or even in writing a new constitution. Another Sunni group, the Iraqi Islamic Party, also rejected offers but agreed to help with the constitution.