On Prophet Street, between the arcade pillars that line the road to Shiite Muslims' holiest shrine, hangs a long black banner. In neatly hand-painted script, it lists members of the Hursan family executed by Saddam Hussein's security men. The memorial stretches over three columns. They contain 22 carefully numbered names.
The former Iraqi dictator's slaughter of Shiite Muslims was particularly brutal. But in a land where rulers have repressed, ignored, or marginalized the Shiite majority for decades, their aspirations pose possibly the greatest single challenge facing the next Iraqi government. Threats from some Shiite leaders of holy war against the Americans could present an even more immediate danger.
The Shiites have not been shy about asserting themselves in the new Iraq. Following orders from their religious leaders, they have taken over neighborhoods in cities across the country, set up armed militias, organized public services and established long-banned political parties in an anxious bid to make their presence felt.
"The Shiite are divided at one level into different political and social orientations," says Ali Allawi, a prominent London-based advocate of Iraqi Shiite rights. But after centuries of domination by Sunni Muslim rulers "they are all united to remove sectarianism from Iraqi politics."
So far, the former Iraqi opposition groups that are expected to form a transitional government under US supervision appear to be taking the same approach, acknowledging the Shiites' 60 percent share of the population. The "leadership council" now drawing up rules for a national conference includes both the major Shiite parties, the Iran-backed Supreme Council for Islamic Revolution in Iraq (SCIRI), and the Dawa.
The American authorities in Baghdad are also dealing with these parties, even though they are mistrustful of their possible ambitions to establish an Islamic state in Iraq, and of their ties to Iran.
SCIRI leader Ayatollah Mohammed Bakr al-Hakim sought to defuse such fears on Tuesday, after his triumphant return from 23 years of exile in Tehran to Najaf.
"We call for an authority that respects Islam and sharia [Islamic law] but not for an Islamic government," he said at a press conference. "We do not believe in copying the Iranian regime."
But in a generally religious country, religious leaders belonging to the Shiite sect have a particularly firm grip on rank-and-file believers.
Shiites, who broke away from the dominant Sunni early in Islam's history in a dispute over the Prophet Muhammad's lineage, are distinguished by their refusal to automatically bow to temporal authority, and by their tradition of ijtihad, whereby sharia is adapted to suit the age.
Shiite Muslims thus rely on religious scholars - ayatollahs and other learned men collectively known as marja - to interpret the Koran and the law in rulings known as fatwas.
The marja, most of whom live in the holy city of Najaf where the founder of Shiism, Ali, is buried, often disagree among themselves on issues of law and religion. But every devout Shiite Muslim must choose his own marja, from whom he takes moral, spiritual, and political guidance.
Such guidance takes on special meaning at such charged and volatile times as Iraq is currently living through.
The most active Shiite religious leader since Hussein's regime collapsed has been Moqtada al-Sadr, a young and relatively inexperienced man who comes from a long line of respected religious authorities. From his base here at the Hawza, the supreme institution of Shiite learning, he has dispatched his agents around the country to try to fill the power vacuum left by the Baath Party.
White-turbaned sheikhs loyal to Mr. Sadr have been active throughout Baghdad and other Iraqi cities for the past month, administering hospitals, organizing garbage collection, trying to restore security, setting up committees to run local neighborhoods in the absence of any meaningful central government, and arranging the return of looted goods to mosques.
Sadr derives most of his popularity from his relationship with his grandfather, Mohammed Bakr Sadr and his uncle, Mohammed Sadeq Sadr, both highly respected religious figures assassinated by Hussein's henchmen.
In the predominantly Shiite Baghdad slum once known as Saddam City, residents have re-named their district Sadr City, and painted new portraits of Mohammed Bakr Sadr on the plinths from which Saddam Hussein's face once beamed.
Sadr is not especially well disposed toward the US presence in Iraq, though his spokesmen say he is grateful for Hussein's overthrow.
"We will not have any contact with the Americans," says spokesman Sheikh Adnan al-Shehmani. "We don't want them to stay. Now they have got rid of Saddam, when they have found weapons of mass destruction they should leave.
"We refuse occupation," he adds. "If the Americans become occupiers, yes, we have to go to jihad. The Shiite taught the world jihad, and the Iraqi people gave millions of their sons to Saddam Hussein. If they were to defy the Americans, they would not find it hard to give millions more."
Despite these bold words, however, the work that Sadr's followers have done to organize communities in recent weeks has sometimes met with a mixed reception.
At the Al Kindi hospital in Baghdad, for example, doctors asked American troops to evict the sheikh who had taken over their hospital, accusing him of interfering in their duties, controlling the supplies of medicines, and writing prescriptions himself.
Nor have the sheikhs' efforts to clean the streets of the capital and keep them safe enjoyed great success, given the lack of garbage trucks and the fact that US troops are now confiscating militia weapons when they see them.
"Up to half the Shiite would probably follow Moqtada al-Sadr's social and political pronouncements," says Mr. Allawi, who has wide contacts in the Iraqi Shiite community. "His organization could fall apart, or it could harden."
Iraq's supreme Shiite authority, Ayatollah Ali Sistani, who heads a moderate and less activist school of thought in the Hawza, has withdrawn from public view in recent weeks, taking a more spiritual approach.
That stands in stark contrast with the most overtly political of the Shiite religious leaders, Ayatollah Hakim, the leader of SCIRI, who made a campaign rally out of his journey through the country this week, complete with advance men, thousands of posters portraying his face, and well organized crowds to receive him in the towns he visited.
Hakim also controls the Badr Brigade, a 10,000 strong Iranian-trained and financed militia composed of Iraqi exiles, some of whom have been reportedly returning to Iraq in recent weeks.
Hakim's vision for Iraq, despite his soothing public reassurance Tuesday that "we will not tread on the rights of others," is not entirely clear. His aides say it is too early to discuss it.
"Our people have to recover from what they suffered," says Adel Abdul Mahdi, a top adviser to the ayatollah. "A drowning person emerging from the water has to get his breath back and we have to give our people time to get back to normal. How can they think now about a socialist state, or an Islamic state or a liberal state?" he asks. "For this transitional period, we have three slogans - freedom, independence, and justice."
Also competing for Shiite political allegiance is the Dawa, a well-organized party whose sympathizers were often the victims of mass executions under the Hussein regime.
In the airy hallway of a former Baath Party building in Baghdad, which the Dawa has taken over as its headquarters, political bureau member Khassem al-Sahlani is cautious about forecasting the future.
"In the beginning, we will try to believe the Americans when they say they have come to help Iraqis," he says. "If what they say turns out not to be true, then the whole Iraqi people will deal with the Americans and prove their sovereignty."
As for his party's program, Mr. Sahlani is equally circumspect. "For the moment the [transitional] government will be a constitutional government, though we hope it will be based on the beliefs of Islam and the nature of Islam. Then it would depend on what the people want."
Some outside observers say they take such careful statements at face value.
"In ijtihad, cost-benefit analysis is acceptable," says Gailan Ramiz, who teaches politics at Baghdad University. "If imposing an Islamic state would lead to civil war, it would be better not to have it."
And some ordinary Shiite believers take a pragmatic approach to the prospect of Islamic rule. "My wish is one thing, and reality is something else," says Imad Abdulaziz, chief engineer at Iraqi TV and Radio. "I would like an Islamic government like when the church ruled Europe in the past, but the fact is that the Americans would not allow an Islamic government."
When the time comes for elections to a permanent government, he says, "I would choose someone who respects the Shiite over a fundamentalist Shiite in power, someone with a modern, flexible approach who gives us freedom to pray. But ideally I would like a modern, educated Shiite."
As the different Shiite political and religious leaders begin jostling for position at the starting line of the race for power and influence in post-Hussein Iraq, some observers fear the competition could turn ugly.
A US-backed reformist sheikh, Abdul Mahdi Khoei, was stabbed to death last month at the shrine to Ali, allegedly by followers of Moqtada Sadr. And Sadr's spokesman, Sheikh Adnan al-Shehmani, was bluntly rude Monday when he compared Ayatollah Hakim's exile unfavorably with the Sadr family's decision to stay inside Iraq under Hussein.
But Allawi is optimistic that such disputes will settle down with time. "It is not possible for any person today in the Shiite world to make a claim to leadership without getting the traditional leadership on their side and getting control of Sadr's organization on the streets," he says.
"There are a number of challenges facing the Shiite community," he adds. "But no single current is prepared to jeopardize the potential gains by insisting on narrow interests. They are all united by a common feeling that unless they present a common front about the empowerment of the Shiites, others might like to divide and rule them."
Islam's most significant split began in 632, with the death of its founding prophet, Muhammad.
One faction of his followers - the Sunnis - claimed that Muhammad wanted his successors chosen by consensus. The Shiites argued that the prophet wanted leaders chosen only from his own family line.
The death in AD 680 of Hussein - the prophet Muhammad's grandson - cemented the rivalry between the two major branches of Islam that continues to this day. Hussein was killed in a battle between Sunnis and Shiites at Karbala, now a modern Iraqi city and a holy shrine for Shiite pilgrims.
The Iraqi city of Najaf serves as the base for Iraq's Shiite clergy. Along with Qom, its Iranian counterpart, Najaf is a center for Shiite religious scholarship and political power. It is also the burial place for Ali, the son-in-law of Muhammad and the founder of the Shiite faith.
Supreme Council for Islamic Revolution in Iraq (SCIRI) - A political group with an armed wing of up to 10,000 fighters. The group existed as an Iran-based exile army when Saddam Hussein was in power. SCIRI is led by religious leader Ayatollah Mohammed Bakr al-Hakim.
The Dawa - A well-organized Shiite political party with collective leadership. The Dawa has taken a guarded but supportive stance on efforts to establish a transitional government.
The Hawza - This Najaf-based group is the supreme institution of Shiite learning in Iraq. Its most prominent leaders today are the moderate Ayatollah Ali Sistani, and the more politically active Moktada Sadr. Mr. Sadr, whose family suffered under the rule of Mr. Hussein, has not been friendly toward the US presence in Iraq and has actively moved to fill the power vacuum left by the collapsed Baath regime.