Ammar Al-Hakim.

When guards in Karbala' waved a Shi'ite religious leader's convoy through a security cordon and into the Imam Hussain shrine at night on Aug. 27, they angered a crowd of rival JaM militiamen and sparked the Aug. 28 fighting which left parts of the city smouldering. The man inside the convoy was Ammar al-Hakim, 36, who emerged this summer as the likely next head of the SIIC - the party which is America's most powerful Shi'ite ally in Iraq. Ammar wears the black turban of those who claim descent from the Prophet Muhammad and was educated in the theological colleges of Iran.

Ammar is far from the urbane, secular, Western-educated men whom US policymakers once hoped could govern Iraq. Yet his family and the SIIC they founded have close ties to Washington. In the last few months, Ammar has taken the helm of the SIIC, stepping into the role of his more reticent father, Abdul-Aziz who is being treated for lung cancer.

Ammar's rise comes at a critical time for the party. The SIIC is the largest Shi'ite party in parliament, but has been losing influence on Iraq's streets to the anti-US Sadr. Ammar's ability to counter Sadr could be crucial to the Bush administration's hopes to maintain support for a continued US presence in Iraq. Theirs is an increasingly violent feud which couples ideological division with dynastic rivalry. It pits the well trained men of SIIC's Badr against Sadr's less disciplined, but larger, JaM.

The Aug. 28 battle in Karbala' sparked reprisal attacks against SIIC offices across Baghdad. Shi'ite leaders, who rarely accuse each other publicly, blamed the violence on remnants of Saddam's regime - a reference to the fact that many Shi'ite Ba'thists of Saddam's regime had infiltrated Sadrist ranks since the early 1990s.

Ammar and Muqada are close in age, and both are charismatic sons of clerical Shi'ite clans which have long vied for leadership among Iraq's Shi'ite majority. But Ammar, a polished orator with a classical Arabic diction, is a sharp contrast to the gruff Muqtada who speaks in the colloquial dialect of the Iraqi poor.

Ammar was groomed from an early age to take on a leadership role. The family home in Najaf was a frequent hideout for wanted men. From the age of four, it was Ammar's job to pass food in secret to the party's fugitives. By the time he was seven, he would help his father elude Saddam's henchmen by acting as lookout. He recently recalled: "I was able to spot the security men even if they were dressed in civilian clothing". From the age of nine, Ammar would address thousands of Shi'ite faithful at mosques and religious festivals in Iran where his family fled in 1979 to escape Saddam's persecutions.

Many in Baghdad and in Washington are suspicious of Ammar's close ties to Iran, where he spent more than half his life. By contrast, Sadr is an Iraqi nationalist who routinely denounces both the Americans and Iranian influence although he, too, has taken assistance from Iran. Ammar has alienated Sunni Arabs by pushing for greater regional autonomy and until recently resisting proposals to give members of Saddam's regime jobs in the government and military. His tendency to travel in flashy convoys studded with gunmen have led some to dub him "Uday" Hakim - after Saddam's corrupt and violent son.

In February, US troops detained Ammar for several hours because of what they said were questions about his passport as he crossed into Iraq from Iran in a heavily-armed convoy. He complained at the time of being blindfolded and searched down to his underwear but accepted an apology from then-US Ambassador Zalmay Khalilzad.

Ammar cautions against a sudden draw down of US forces, which he says would be dangerous for Iraq. He says he supports a US-sponsored bill governing the distribution of Iraq's petroleum wealth. He expresses willingness to compromise with Sunni Arab politicians.

At a time of mounting frustration with Maliki, Ammar distances himself from moves to replace him. But analysts say it is too soon to determine whether Ammar intends to chart a course similar to his father's, or whether he could steer the SIIC in a new direction. Like his father, who has tried to make top SIIC official Adel Abdul-Mahdi PM, Ammar may prefer the role of king-maker. But it remains to be seen whether he can compete against Sadr and other Shi'ite leaders.