To find the U.S. troops responsible for security in this southern Iraqi city, leave Najaf, head for the desert and drive for 40 minutes. The troops are out there at an isolated base, while Iraqi policemen and soldiers patrol the city.

Najaf is touted by the U.S. military here as a potential model for the withdrawal of U.S. forces from Iraq: Get the American soldiers off the streets and pull them back to bases outside the cities until things are quiet enough for them to leave for good.

"We only go down there if they call us. And that doesn't happen very often," said Sgt. 1st Class Paul Bedford of Smithville, Miss. "Usually, we just stay out of their way," said Bedford, who runs reconnaissance patrols from the desert base, Camp Duke.

But Najaf, a city of 500,000 about 90 miles south of Baghdad, runs according to its own rhythms and so may not be a good model. It has been deceptively quiet and calm for long stretches punctuated by sudden violence, and has not experienced the chronic Sunni Muslim-based insurgency and random attacks that have terrorized Baghdad and central and western Iraq.

Moqtada Sadr, the radical Shiite Muslim cleric, wields considerable power here and commands a loyal following and a strong militia. On Thursday, he lambasted President Bush's plan for Iraq as "an insult to international opinion."

In an unusual public appearance, Sadr said Bush's refusal to set a timetable for a U.S. troop withdrawal was an affront to Iraqi parties meeting in Cairo that had issued a statement demanding a scheduled pullout. A fixed timetable would lead to "stability in Iraq and all the countries of the region," Sadr said.

Despite the criticism, the members of the Mississippi National Guard unit at Camp Duke said that the Najaf operation was a successful one that could be duplicated elsewhere, noting that they had been in the area for 11 months without a fatality.

"I do think this serves as a model," said Lt. Col. Jim Oliver, 46, of Brandon, Miss., commander of the guard unit, the First Battalion of the 198th Armor Regiment, based at Amory, Miss. "We have had two elections and three or four major religious events, and they have all been safe and successful," he said Thursday.

"Could this function without U.S. presence at all? Yes," Oliver said. "We could pull out all of our troops from Najaf. But I would rather hedge my bets and keep some presence here."

Najaf, which sprawls among date palm trees along the Euphrates River, is one of Shiite Islam's holiest sites. The city hosts more than a million pilgrims every year, the most pious trudging by foot to reach the dazzling Imam Ali shrine in the city center.

In August 2004, U.S. troops fought a fierce battle with Sadr's militia, the Mahdi Army, among the vast tombs of the cemetery beside the gold-domed shrine. The battle, which threatened to spread to the rest of the country, ended in a truce.

At least 50 people were killed in December 2004 when a huge car bomb exploded several hundred yards from the shrine.

Fighting erupted this August between Sadr's followers and rival Shiite fighters, and at least six people were reported killed. But, said Oliver, "The good news was that we didn't get involved in that at all. The local government handled it."

In September, the Mississippi guardsmen handed over responsibility for security in Najaf and the neighboring holy city of Karbala to Iraqi forces and relinquished control of Camp Hotel, their large base just outside Najaf. The Iraqi army renamed the base and has painted the high, concrete walls with colorful murals of stallions and camels.

"There is freedom in Najaf that there isn't in Baghdad," said Asaad Abu Gelal, the governor of Najaf province. "The Americans are out of Najaf. They are far off."

The arrangement has permitted Oliver and his troops to concentrate on more than $50 million worth of reconstruction projects in the area. They have expanded a local hospital, built schools, rehabilitated the sewage treatment system and opened a sparkling soccer stadium with towering lights for night games.

Oliver led reporters on a tour of a green-tiled riverside pavilion being completed at Kufa, on the edge of Najaf, a popular gathering spot and traditional destination for brides on their wedding day.

"It is a PR project," Oliver acknowledged. "We saw the positive feedback we were getting from the soccer stadium, and we wanted a big impact to turn some of the sentiment and sympathies of the town to us."

Oliver said he saw his job as a battle to win over Iraqi sympathies, in competition with Sadr, a fierce critic of the Americans. At present, Oliver is working to dispel rumors that Americans deliberately killed and tried to behead a suspected bomb maker. He said the man had been killed by Iraqi police.

But the real success, Oliver said, is that Iraqi troops, rather than Americans, are now on call to defuse roadside bombs when they are found. Iraqi police are first responders to calls reporting trouble in the city.

"We are now just oversight and support," he said. "We really try to stay in the background."

That worries some Iraqis. "Some of the Iraqi forces have militia in them," said Ahmed Noori, an engineer and secular candidate in the Dec. 15 parliamentary elections. "The problem is their loyalty. Are they loyal to the military and police or to a religious party?"

The governor, Gelal, whose administration has been controversial because of his ties to an Islamic party with a militia, denied that the security police had been infiltrated. "There is no militia in Najaf," he said. "The Iraqi army and police are working fairly. There is no militia."

Human rights activists in Najaf have reported allegations of torture of prisoners by the security forces and suspicious killings.

Ahmed Fatlawi, one of the activists, said such torture could increase with an early U.S. withdrawal.

"It's a big gamble for the U.S. forces to leave at this time," he said.

U.S. troops inspect the site of an attack on a U.S. military convoy near Najaf on Wednesday. Iraqi forces have largely assumed responsibility for security in the area. "We are now just oversight and support," Lt. Col. Jim Oliver said.Moqtada Sadr, who is based in Najaf, lambasted U.S. plan for Iraq.