In the shadow of Sistani.

The first time I asked a U.S. military commander about the young cleric Moqtada Al-Sadr, in Najaf, the response from the Marine was: "We think he's on drugs." This was in September 2003, a few days after Sadr, who is the son of a famous cleric slain by Saddam, announced he was forming a militia. The following August, Sadr's militia clashed openly with the U.S. military. Since then, his power has only grown.

But if the American military still downplays Sadr's influence, the Iraqi government is trying not to make the same mistake. Over the summer, Prime Minister Ibrahim Jaafari visited Sadr on the same day he traveled to Najaf to visit the Grand Ayatollah All Al-Sistank A year ago, this sort of recognition would have been unthinkable.

And when tensions reached a boiling point this May between Sunni leaders and the Supreme Council for the Islamic Revolution in Iraq because of allegations that the council's Badr security forces have been rounding up and killing Sunnis, it was Sadr who mediated between the two groups.

In October, Sadr announced for the first time that he would actively encourage his followers to run in U.S.-backed elections for the national assembly, a body that is increasingly focusing on evicting the American military through legislative means. Sadr joined forces with the United Iraqi Alliance, which means that his candidates will run on a ticket with the Supreme Council for the Islamic Revolution in Iraq and Jaafari's Dawa Party. The move is a canny way to prevent Shiite voters from having to pick between candidates at the polls.

Currently, Sadr counts on twenty-four members of parliament, as well as three ministers. In the areas controlled by those ministries, women complain of being forced to dress in accordance with Islamic law. And the Sadrist minister of transportation has taken liquor out of Baghdad's duty-free shop at the airport.

Ali is a musician in Sadr City, and since the invasion, he has not been able to play in public for fear of retribution from militias.

"In the past, we used to do our job normally," says Ali. "But the current government does not care enough to protect us because the Islamists think that music affects Islam negatively."

Vehemently nationalist, Sadr appeals to a younger generation of Shiites and to some disenfranchised Sunnis. His power belies the simplistic Shiite vs. Sunni story that the mainstream media have been peddling. The rift among the Shiites also threatens the stability of Iraq.

In August, Sadr brought out hundreds of thousands of followers to protest policies of the Jaafari government. And members of Sadr's militia clashed with police forces across the south, as well as in Baghdad, when the Supreme Council's militia tried to prevent the reopening of Sadr's office in Najaf.

This was by no means the first clash. In August 2004, Sadr's forces were fighting a losing battle against U.S. troops, Iraqi troops, and the Badr militia in Kufa and Najaf. The standoff ended with the storming of the Imam All shrine, led by members of the Badr militia. The council's forces in the south have continued to arrest members of Sadr's movement.

Hadi Al-Amary is a member of the Iraqi national assembly and a leader of the Supreme Council's political wing. He defends his militia's participation in the effort to put down Sadr's forces.

"Whenever there is terror, we should stand against it," he says. "We should go against the terror if it is Shiite or Sunni."

As Amary spoke, a demonstration was going on outside the Green Zone. Dozens of young men claimed they had been removed from the police force simply for being followers of Sadr. (The Supreme Council controls the ministry of interior and the police, so from their perspective, it makes sense to purge the Sadrists.)

Amary blamed the Americans.

"It is in the hands of the Americans, not the hands of the Badr," he said. "This is one of the problems: We have a lack of sovereignty within the ministry of interior."

Sadr is as canny a politician as any in the country, including Ahmad Chalabi and Ayatollah Sistani. And Sadr's power, in the shadow of Sistani's, should not be underestimated.

For the October referendum on the constitution, Sadr initially threatened to call on his followers to vote against it but then backed down. He was embarrassed by the publication of a message, purportedly from Abu Musab Al-Zarqawi, that his insurgent forces would make an exception for Sadrists in the "war against the Shiites." According to news reports, Sadr went to Ayatollah Sistani and asked for advice and then followed Sistani's wishes on the constitution.

With the end of the fighting in Najaf and Kufa in the summer of 2004, much of the Sadr movement was forced underground, where it has been slowly regrouping.

"The people who are in prison have already begun to organize," said Sayyed Kanan Mousawi, one of the heads of the recently reopened Sadr office in Basra. "The movement is growing. We are concentrating on the youth."

Mousawi, an engaging man in his mid-twenties who chain-smokes, said that the new office would provide military training for the Jesih Al-Mehdi, the militia that battled U.S. troops last August. Mousawi said the militia would be for national defense only.

"It will be a military, not a militia," he said. "We will offer our assistance to any national Iraqi government. Every country all over the world needs to have their own army to defend their cities, and we see that the Iraqi army is not doing this job sufficiently."

When I mention the events of last summer, Mousawi laughs and makes little shooting noises with his mouth while miming holding a Kalashnikov.

"I was in Kufa," he says, smiling.

Mousawi admonished a translator who accompanied him to our interview when he used the word "Hezbollah" to explain the model for the new militia. The Sadrists, in their media efforts, are careful to distance themselves from the Lebanese group, though they have friendly relations.

Sadr's movement has opened offices in Beirut's southern suburbs to allow representatives easy access to foreign embassies and media outlets. Running the Beirut office is Hassan Zarkany, one of the leaders of the movement, which also has offices in Damascus and Tehran.

Zarkany formerly ran Al-Hawza, the pro-Sadr newspaper that was shut down by the U.S. military in March 2004 for a couple of months, a foolish move that radicalized the Sadr movement. He has remained outside Iraq since then for fear of being arrested.

"We keep track of what the media is saying and we also go on satellite TV," he says. He adds that he has participated in a number of conferences and has traveled out of the country to participate in anti-occupation forums, including a meeting in March with remnants of the Baath Party.

Like Mousawi, Zarkany sees a distinct generational gap among Shiites. He believes that young people resent Ayatollah Sistani's refusal to condemn the U.S. occupation and that Sistani's patronage, along with Iran's, is the only thing that allows the Supreme Council to maintain a hold on power. The Sadrists, Zarkany says, are the true Iraqi Arab nationalists.

"My parents are with the Badris because of the influence of Sistani," Mousawi said. "But me and my brothers, we are Sadris. The Badris have sold out to Iran. The only way to stop them is to cut their money from Iran. They cannot defend a country if they have sold themselves to another country."

The ever-scowling Moqtada Al-Sadr and the ever-smiling Sayyed Hassan Nasrallah, the leader of Hezbollah's armed resistance, appear on posters together all over Sadr City. Sadr's office there, leveled last year by tanks belonging to the U.S. Army's First Cavalry division, has been rebuilt to twice its size, and always seems full. Outside, boys hawk copies of Al-Hawza and other publications dedicated to the movement's line.

Little donation boxes for Sadr's group have started appearing in Baghdad, just as they dot the southern suburbs of Beirut for Hezbollah.

In Sadr City, shrines stand where residents dismantled American armored vehicles during last year's fighting. At that time, I sat in one of the offices there as families returned the meager monies provided for a "shaheed" funeral, saying things like "Sayyed Moqtada needs it more."

Down in Kufa, the mosque where Sadr's father sermonized was reopened for prayers in February after having been closed since last August.

It's not hard to find discontent with Sistani here.

"Sistani issues a fatwa for people to vote, but why doesn't he issue one regarding the lack of electricity or fuel or for the Americans to leave?" one of the men at prayers asked.

Sadr's popularity is a warning: Those who supplant Sistani will be even more radical.

Illustration by Tra Selthrow

David Enders is the author of "Baghdad Bulletin" and a contributor to motherjones.com and The Nation.