It seemed a reasonable enough request. But Sistani’s appeal was also striking in its limited ambition. For months, calming statements from the ayatollah held Shiites back from retaliating for killings by Sunni insurgents. But three years of insurgency, sectarian tensions and miserable living conditions have shrunk the space for temperance and given extremists plenty of room to operate. “[Sistani] doesn’t have the same degree of influence,” says Joost Hilterman, director of the International Crisis Group’s Iraq program, based in Jordan. “He may be saying the same things, but fewer people are listening to him.” As much as anything, the battle now is about which voices will shape the future of Iraq.

Not too long ago Sistani would have won that contest hands down. When Moqtada al-Sadr, the young radical Shiite leader, laid siege to the Imam Ali shrine and fought U.S. Marines to a standstill in Najaf in the summer and fall of 2004, Sistani put an end to the insurrection in a matter of days upon his return from London, where he was receiving medical treatment. He successfully lobbied to hold elections on an Iraqi timetable and convinced U.S. officials of the need for a referendum on the Iraqi constitution. Sistani’s calls for unity after bombings of Shiite shrines worked for a remarkably long time.

But last February, when terrorists struck one of the most important sites in Shia Islam, the Askariya shrine in Samarra, it unleashed a wave of bloodshed that even Sistani couldn’t control. “I reiterate my appeal to realize the magnitude of the danger threatening the future of [our] country,” he said after the Samarra bombing. Since then the violence has only gotten worse, and Sistani has retreated further into his inner sanctum. “We have noticed that some people feel [Sistani’s] calls for restraint aren’t protecting them,” says Shiite politician Ali al-Dabbagh, who consults with Sistani on a regular basis. “We notice gangs coming out doing revenge. If the violence continues there will be more and more people who won’t listen to calls for restraint.”

The astute Sistani may be keeping quiet precisely because he realizes the limits of his power–and wants to husband what’s left of it. “What would be the decisions that Sistani can make in these circumstances?” says Ihsan Abdul Ridha, 40, a computer technician in Baghdad. “What is the power he has while sitting inside his four walls?” Sistani’s constituency, too, has changed, says the ICG’s Hilterman. “Sistani’s people are still there, but it’s mostly elite Shiite support,” he says. “The Street is increasingly prone to supporting militias and radical preachers who say what they like to hear–take revenge for the killings.”

Even the ayatollah’s closest advisers know that his most powerful weapons–the fatwas , or binding religious edicts, that he can issue–no longer carry the same weight among this desperate population. They see no point in undermining his authority any further. “Some people ignore those instructions,” says Hamid al-Khalaf, a chief Sistani spokesman. “What can we or the clergy do? This ignorance is one reason behind [Sistani’s] being silent.” Sheik Maher Hussein al-Hamra, a Sistani aide in Baghdad, agrees: “It is wise now to keep silent. What can Sistani say?”

The problem is that militia leaders are using Sistani’s weakened position to carve out bigger roles for themselves. One such radical is Mahmoud Hassani, a Shiite preacher in Karbala whose forces recently engaged in skirmishes with U.S. forces. Hassani has publicly criticized Sistani, and challenged his religious authority on several occasions. Like the fighters in Sadr’s Mahdi Army, Hassani’s followers are armed and pushing for further confrontation. Last week, Shiite militiamen staged a demonstration in the Shiite stronghold of Khadimiya, where they heaped abuse upon Sistani’s chief representative in Baghdad, the revered cleric Hussein al-Sadr. Marching through the streets, hundreds of young men chanted “Damn the one who embraced Bremer,” a reference to an incident in 2003 when the Sistani representative embraced former head of the Coalition Provisional Authority Paul Bremer during a meeting recorded by TV cameras.

To be fair, Sistani never wanted the spotlight. Before the war he was a quiescent Islamic scholar in a long tradition of Shiite moderation. After the invasion, when Iraqis called for him to take more of a leading political role, he went along. His primary goal was to ensure that the long-oppressed Shiite majority gained its rightful place at the table. He succeeded in that aim, but at the cost of making himself indispensable to the political process.

Now, having pushed hard for a strong political class, Sistani has no choice but to accept what it delivers. “He is concerned about the security threat. But if he is viewed as the éminence grise that defines political outcomes, that would be a step back [politically],” says a high-ranking U.S. military-intelligence officer in Baghdad, who asked to remain anonymous because he is not authorized to speak publicly to the press on sensitive issues. Al-Dabbagh recently asked Sistani what he thought of federalism, and was told that he didn’t think anything–it was an issue for Iraqis and their elected representatives to figure out. “He’s still playing a quiet role,” says Dabbagh. But by limiting his public comments, “politicians will be freer to make decisions and be held accountable.” The problem is that Sistani, with his moderate ideas on religion and democracy, may be one of the few forward-thinking leaders left in Iraq. The ability of his words to sway, or even save, a nation may be fading at just the wrong time.