A Saudi initiative to send an Islamic force to help stabilize Iraq and reduce the need for the U.S.-led military force would probably take three months or longer to deploy and might not get off the ground at all, according to U.S. and Iraqi officials. The proposal is already mired in complex military issues and political sensitivities.

The logistics and diplomacy are so daunting that, even if there is an agreement to form such a force, the first major deployment might not happen until well into the fall, and a full deployment until much later, potentially too late to make much of a difference in securing Iraq before campaigns begin for national elections due in January, the officials said.

But the pivotal issue is more likely to be whether the force, drawn from Arab and Muslim countries, would bolster the 160,000 foreign troops in Iraq or come in as a separate force and begin to replace them. The difference could make or break the Saudi idea, the officials said.

The United States has politely welcomed the proposal since it was outlined in talks Wednesday between Saudi Crown Prince Abdullah and Secretary of State Colin L. Powell. The Bush administration was in no position to reject the idea out of hand, U.S. officials said, because it came from a crucial oil-rich ally and because the United States has struggled to find new troops for the multinational force.

But the initial U.S. reaction was quickly tempered by officials who have used cautionary language in public and expressed deep skepticism in private.

"We appreciate the initiative, but it has to be studied in depth," Powell said tersely on Saturday after talks with Kuwaiti leaders. The proposal caught Powell's entourage off guard by unexpectedly dominating the secretary's week-long trip to the Middle East and Eastern Europe.

In Baghdad, Powell found some skepticism among Iraqi officials, who were wary about how a separate new force would work or replace the U.S.-led troops, and about Saudi goals in proposing the initiative.

"We will not close the door, but I don't think it's going to fly as the Saudis proposed it," a senior Iraqi official said on condition of anonymity because discussions have just begun.

During three weeks of behind-the-scenes diplomacy, Saudi Arabia, home to Islam's holiest sites, has canvassed allies about a Muslim force to gradually reduce and potentially replace the U.S.-led force. One goal is to reduce the mounting animosity against the United States and the West in the Islamic world sparked by the invasion of Iraq, which in turn has made governments allied with the United States vulnerable, Saudi officials said.

The officials said the proposal was also the only way to win Muslim troop commitments, because most Arab and Islamic countries would probably reject the idea of offering troops as part of the current U.S.-led force. Countries that border Iraq, such as Saudi Arabia and Jordan, would not be included, Saudi officials have said.

But U.S. officials said the Bush administration wants any new troops incorporated into the current multinational force, which is due to stay in Iraq at least through an 18-month transition until the first elections for a permanent government were held, and possibly much longer. Powell said Friday during a stop in Baghdad that the United States supported "the concept" of Muslim forces in Iraq, but did not extend that further to embrace the Saudi idea of a separate force.

The United States has made repeated overtures to several Muslim countries, notably Pakistan, to join the current force or contribute troops to a separate small protection force for U.N. personnel sent to help set up elections and do humanitarian work. But all U.S. requests have been spurned, the officials say.

Shortly after assuming office on June 28, interim Prime Minister Ayad Allawi wrote to several Muslim countries, including Bahrain, Bangladesh, Egypt, Morocco, Oman, Pakistan and Tunisia, to appeal for troops. But, like the United States, the new Iraqi leadership strongly favors adding them to the current U.N.-approved force.

Arab countries are discussing ways to help Iraq, according to Kuwaiti Foreign Minister Mohammed Sabah. "We had a very constructive neighboring countries meeting in Cairo two weeks ago. We agreed that Iraq needs all the help it can get from its Arab brothers and its Islamic brothers," he said after talks with Powell.

But many of the countries are also caught between a desire to ensure that instability in Iraq does not spill over into the region or spawn another Afghanistan-like refuge for Islamic extremists and the dangers of getting enmeshed in Iraq's deadly insurgency, Arab officials said. The recent spate of abductions in Iraq, when Muslim civilians from Somalia, Pakistan and Egypt were among those seized, may not make the decision any easier, they added.

The idea of eventually allowing Muslim forces to replace the U.S.-led force introduces an awkward numbers game, U.S. and Iraqi officials said. The Saudi proposal calls for a one-for-one troop swap, they said, which may not be viable to contain or defeat the insurgency. Most troops from Muslim countries are not as well trained or well equipped as the U.S., British, Polish, Australian and Ukrainian troops that make up the bulk of the current force.

"Whether the idea is one-for-one or 10-for-one, it's not a good idea," the senior Iraqi official said. "There's no way the Bangladeshi army can or will replace the current multinational force."

For the United States, another major question concerns the chain of command, or how to coordinate with the military leaders of a separate force operating in the same or nearby areas, according to U.S. and Iraqi officials. In the past, the United States has insisted on maintaining a single chain of command in war zones, including Iraq.

The Saudis have suggested that a Muslim force operate under a U.N. umbrella -- something the Security Council and U.N. Secretary General Kofi Annan have previously been unwilling to consider. It would also require a U.N. resolution.

In interviews Friday, Iraqis expressed uncertainty and confusion about the idea. Some said they feared that Iraq's neighbors would use the initiative to undermine Iraqi sovereignty, and they echoed the widespread belief that many recent bombings and other violent attacks had been committed by foreign Islamic extremists.

"I prefer that they don't come, especially from the nearby countries. They are the ones who are behind the explosions and the bombs, and we don't believe they want to benefit Iraq," said Mukdam Amir, 25, a shoe store manager.

In a sermon at Friday prayers in the city of Kufa, Moqtada Sadr, a powerful radical Shiite cleric with a large, youthful following, condemned the idea, saying: "We advise Arab and Islamic countries to refuse to send their troops. Even if they are Islamic and friendly, if they come to Iraq that means they are cooperating with the occupiers. Thus they will be considered occupiers, too."

Correspondent Pamela Constable in Baghdad contributed to this report.

Secretary of State Colin L. Powell, left, and Saudi Foreign Minister Prince Saud Faisal, spoke at news conference in Jiddah Wednesday.