Shiite militiamen loyal to radical cleric Muqtada al-Sadr (search) clashed Thursday with Sunni militants in fighting that killed at least 15 people, and three American soldiers died in separate attacks the day before, officials said.
Six Iraqis died and 12 were wounded in other attacks Thursday.
The Shiite-Sunni fighting occurred after al-Sadr's Madhi Army (search) militia raided a house in Nahrawan, 15 miles southeast of Baghdad, to free a fellow militiaman kidnapped by Sunni militants, said Amer al-Husseini, an aide to al-Sadr.
The Mahdi Army freed the hostage and captured two militants during the raid, but was ambushed on its way out of Nahrawan (search), al-Husseini said.
Police Maj. Falah al-Mohammadawi said the 15 deaths included 14 Madhi Army members and a policeman. He said 14 people were wounded, two policemen and the rest either militia members or civilians. No insurgent casualties were reported.
The incident underscores tensions among hard-line elements in Iraq's rival religious and ethnic communities at a time when the United States is struggling to promote a political process seen as key to calming the insurgency so that U.S. and other foreign troops can go home.
As part of the political process, Iraqi parties are trying to put together coalitions to contest the Dec. 15 parliamentary election following ratification of the constitution in a referendum Oct. 15.
Three Sunni Arab groups — the General Conference for the People of Iraq, the Iraqi Islamic Party and the Iraqi National Dialogue — joined forces to field candidates in the election, which was made possible by the newly ratified constitution.
But an influential group of hard-line Sunni Arab clerics, the Association of Muslim Scholars, denounced the constitution and said they will not join the political process.
Those contradictory statements signaled confusion within the minority Sunni Arab community, which forms the core of the insurgency, on how to go forward after it failed to block ratification in the referendum.
Shiite politicians said talks were continuing Thursday on a joint Shiite ticket.
As politics intensified, the fighting continued.
Two U.S. Army (search) soldiers were killed Wednesday when their convoy hit a roadside bomb in eastern Baghdad, the military said. That same day, a roadside bomb and small arms fire struck an Army patrol 37 miles north of Baghdad, killing one American soldier and wounding four, the military said.
The deaths raised to at least 2,004 the number of members of the U.S. military who have died since the beginning of the war in 2003, according to an Associated Press count.
In Baghdad (search) on Thursday, a suicide attacker rammed his car into a U.S. military convoy in Karradah, a commercial and residential district, killing one Iraqi passer-by, wounding nine others and damaging two parked cars, said Capt. Mohammed Abdul Ghani. One soldier suffered a concussion, the military said.
In Dora, one of the capital's most violent areas, a drive-by shooting by insurgents killed police Lt. Colonel Mahdi Hussein, officials said. A similar attack killed a pedestrian in central Baghdad, said police 1st Lt. Mohammed Khayoon.
Three other Iraqis were killed outside Baghdad.
In the oil-rich city of Kirkuk, 180 miles north of the capital, a police officer died of wounds suffering in a drive-by shooting, and two bomb attacks aimed at police patrols killed one policeman and wounded six, officials said.
In Fallujah, 40 miles west of Baghdad, insurgents fired a mortar round at the Iraqi army headquarters, leading soldiers to return fire randomly and hit a nearby car carrying three teachers to a school, said police 1st Lt. Assad Hussein al-Jumaili. One of teachers was killed and two were wounded, he said.
On Wednesday, U.S. aircraft destroyed more militant safe houses near the Syrian border, and apparently killed a senior al-Qaida in Iraq figure who was using religious courts to try Iraqis who supported coalition forces, the military said.
Earlier this week, Iraq's election commission completed an audit on the results of the constitutional referendum, saying the document had passed by a large margin, thanks to the support of Kurds and majority Shiites.
Many Sunnis opposed the constitution, fearing it could lead to the breakup of the country into semiautonomous regions favoring rival Kurds and majority Shiites.
Sunni Arabs also largely boycotted the Jan. 30 parliamentary election, enabling the Shiites and Kurds to win an overwhelming majority and shape the constitution.
U.S. officials see Sunni Arab participation in the December election as a hopeful sign that more and more members of the community will forsake the insurgency, enabling the U.S.-led coalition to begin drawing down its forces next year.
As Sunni groups were coming together, the Shiite United Iraqi Alliance, which swept most of the parliament seats in January, appeared to be fraying.
Iraq's leading Shiite cleric, Grand Ayatollah Ali al-Sistani, has decided not to endorse the Shiite coalition which ran under his banner in January, according to associates on both sides.
Close associates said al-Sistani's decision reflected his disappointment with Prime Minister Ibrahim al-Jaafari's Shiite-led government. Al-Sistani's endorsement of the Shiite coalition was seen as the principal reason for its success in January.
If al-Sistani does not change his mind, the December election could produce a major realignment of the political landscape. It remains unclear, however, whether political change will produce a quick decline in the insurgency.