BAGHDAD, Iraq – Radical Shiite cleric Muqtada al-Sadr has ordered his militia not to confront U.S. forces and has endorsed negotiations aimed at easing the deployment of American troops in his strongholds, according to Sadrist and other Shiite officials.

Ahead of a planned surge of 21,500 U.S. troops intended to secure Baghdad, the cleric has instructed his al-Mahdi Army, recently described by the Pentagon as the biggest single threat to a stable Iraq, to keep a low profile and stay off the streets, Sadr officials say.

A deal with the supporters of the fiercely anti-American cleric would temper U.S. military commanders’ concern that any attempt to secure Baghdad will inevitably lead to a showdown with Iraq’s biggest private army. In 2004, the U.S. military fought bloody battles with the Mahdi Army in Najaf and in Sadr City, a sprawling Shiite enclave in Baghdad, and has since steered clear of direct confrontations with the militia.

The Sadrist movement has given its blessing to an initiative led by one of two mayors of Sadr City to negotiate terms under which U.S. forces will be able to deploy freely there.

If the negotiations succeed, U.S. forces will be welcome in Sadr City, the Mahdi Army stronghold that has witnessed two previous battles between U.S. troops and the Shiite militia, said Rahim al-Daraji, the mayor of the southern half of Sadr City. Al-Daraji said he has been authorized to negotiate on behalf of the Mahdi Army and other Shiite factions.

“It will mean any U.S. soldier will be as welcome in Sadr City as any Iraqi citizen,” said al-Daraji, who said he is politically independent. “He will be able to walk safely in Sadr City, sit in any restaurant he likes, and he can help in reconstructing the city.”

Al-Daraji says he has met with coalition military and U.S. Embassy officials three times since President Bush’s revised strategy for Iraq was announced. The U.S. Embassy declined to confirm or deny that the meetings had taken place.

“U.S. Embassy officials meet with those who have an interest in Iraqi affairs on a routine basis. We do not generally disclose the substance of those meetings,” embassy spokesman Lou Fintor said.

Jamal al-Shammari, a senior Sadr official in Baghdad, said the Sadrist movement refused to enter into direct negotiations with the U.S. but approved of “indirect negotiations” that would avert confrontation between the Mahdi Army and U.S. forces.

“There are strict orders to Sadr followers by their leaders to support the new security plan and not to clash with U.S. or Iraqi security forces,” he said.

If Sadr orders his militia to lie low, there is a good chance his largely volunteer militia will survive the latest threat to disband militias, enabling it to re-emerge once U.S. troops start to leave, said Joost Hiltermann, who is based in Amman with the International Crisis Group.

“Muqtada’s playing it clever,” he said. “The Mahdi people are just going to melt away.”

Iraqi Sunnis worry that any settlement with the Shiite militia will leave Sunnis as the chief targets of stepped-up security operations, thereby deepening the vast sectarian divide. The Shiite militia is suspected of being behind most of the death-squad killings that have driven Sunnis out of many Baghdad neighborhoods, helping fuel Sunni support for the insurgency.

“This is a new thing. The security plan doesn’t talk about deals with militias,” said Naseer al-Ani, a parliamentarian with the Sunni Iraqi Islamic Party who said he was unaware of the negotiations. “The security plan aims to chase down and eliminate all militias. The Mahdi Army is a militia, so they have to chase it down.”

Prime Minister Nouri al-Maliki is allied with the Sadrist movement, whose parliamentarians were instrumental in securing his election to the premiership, and most Sunni politicians say they don’t trust government security forces to treat Shiites and Sunnis equitably.

Shammari, the Sadr official, said al-Mahdi Army fighters won’t surrender their weapons but would leave their guns at home and return to their normal lives for the duration of the new security plan.

“If the security plan works and terrorism ends, there will be no need for the Mahdi Army,” he said.

The Mahdi Army controls numerous Shiite Baghdad neighborhoods beyond Sadr City, and some residents say they have noticed fewer gunmen on the streets recently. That may be because hundreds of thousands of Shiites are converging on the holy Shiite city of Karbala for the annual Shiite Ashoura festival.

But there has been no discernible change in the violence in the capital. Police are still recovering each day dozens of bodies killed by death squads, and a surge in bombings against mostly Shiite civilian targets killed more than 150 people last week.

It is still not certain the negotiations will succeed. The mayor of Sadr City’s northern sector, Hassan Karim, a Sadrist appointee, said he supported al-Daraji’s efforts to negotiate the entry of Iraqi security forces into Sadr City, but hoped he would not agree to the deployment of U.S. troops.

“If the government sends troops, police or army, they will be most welcome and there will be great cooperation by the people of the city with these forces,” he said. “But not with the American forces, absolutely not. We reject their presence, not only in Sadr City but all over Iraq.”

“Rahim al-Daraji is an official … of the city. He knows what he’s doing, and we’re not against him having negotiations,” he said. But, Karim cautioned, “he does not represent the Sadrist tendency, and he doesn’t represent all of Sadr City.”