A Shiite political battle - ostensibly over constitutional differences - erupted between two powerful militias and spread throughout Iraq Wednesday night and Thursday.
Moqtada al-Sadr's Mahdi Army locked horns with the Badr Brigade, the militia of the ruling Shiite religious party the Supreme Council of the Islamic Revolution in Iraq (SCIRI), signaling that the fight for control of a new Iraq goes beyond the conflict between Shiite, Sunni, and Kurd.
The fighting in southern and central Iraq, where at least nine Iraqis were killed, springs from an emerging power struggle between Mr. Sadr's movement and SCIRI.
The two groups have been at loggerheads since Sadr's militia won popular support after confronting US forces last August in the city of Najaf. The Badr forces have seen their influence rise after the SCIRI slate swept January's elections.
Politically, Sadr and the ruling Shiite parties have battled throughout the drafting of Iraq's constitution. Sadr has forcefully objected to a SCIRI-backed provision expanding federalism to give the Kurdish north and Shiite south semiautonomous status.
Just last week Sadr and imams loyal to him led protests after Friday prayers where hundreds of followers chanted, "No! No! Federalism, Yes! Yes! Unity." More demonstrations were planned for Friday to protest the lack of basic services like electricity and water.
While Iraqi officials said Monday they would finish the draft of the constitution by Thursday at midnight, by the Monitor's deadline it appeared no progress had been made.
For the fighting that broke out Wednesday night in the Shiite holy city of Najaf, Sadr blamed Badr Brigade leaders, and vice versa.
Abbas Rubaie, the political director of the Sadr movement, said Thursday that Badr Brigade members, with the help of local police and approval of the SCIRI-loyal local governor, attacked a Sadr office in Najaf, killing guards and several men inside.
Fighting cooled Thursday afternoon after Sadr issued a statement calling for calm. He thanked the government for their calls for peace, but not "the interior minister," Mr. Rubaie said, reading a statement from the cleric. The interior ministry, controlled by SCIRI, runs the police forces and is believed by many Iraqis to be dominated by the Badr Brigade.
Sadr views SCIRI and the Dawa Party, another Islamist Shiite party that shared a ticket with SCIRI in January's election, as simultaneously too loyal to Iranian and American interests.
Over the past year the Sadr movement, as they call themselves, has focused on solidifying their base by widening the social services network and organization of the Mahdi Army.
When asked if Badr was trying to rein in the power of the Mahdi Army, Rubaie was incredulous. "They can't!" he said, insisting that Mahdi Army members far outnumbered Badr forces.
Hazem al-Araji, a top adviser to Sadr, who heads the social services network, said Mahdi Army members in violent areas of Baghdad and southern Iraq still carry weapons.
But in calmer neighborhoods they mainly work guarding high ranking clerics and mosques. In the peaceful Kadhimiyah neighborhood where Mr. Araji is based, he says the Mahdi Army even works with the Iraqi police and army.
"Everywhere there is cooperation together of the Mahdi Army and [Iraqi police and army]," says Araji. "There is a liaison between us and the army and police."
Analysts have drawn parallels between Hizbullah's activities in Lebanon in the 1980s and Sadr's militia today.
"Both groups are antiestablishment, not just anti-American," says Amal Saad-Ghorayeb, an expert on Hizbullah in Lebanon and author of a book on the group. Providing social services "played a very large role in expanding Hizbullah's support base ... [but] the resistance [to Israeli occupation of southern Lebanon] more than the social services [was the reason] for their support."
Indeed, Sadr himself is often pictured in montages with Hizbullah leaders. More than 100 religious colleges have been opened by the Sadr movement to train religious leaders, and so far the Sadr movement has spent some $70,000 on payments to destitute families and families of Mahdi Army members killed last August and in an earlier clashes, Araji says. The number of families dependent on Sadr's welfare grows every month.
• Alan Enwia contributed to this report.