President Bush last week laid out an American role in the upcoming Mideast peace talks that challenges the accumulated wisdom of former secretaries of State Henry Kissinger and James A. Baker III and Presidents Carter and Clinton.

But sticking to his plan, which calls for a carefully limited U.S. role, may be harder than the president thinks, say current and former diplomats who have wrestled with the issue.

Bush has defied a diplomatic consensus reaching back decades by insisting that the United States would encourage Israelis and Palestinians and would offer ideas if asked, but wouldn't sit continuously at a negotiating table or establish positions of its own.

The conventional approach, based on more active American prodding, simply "hasn't worked," Secretary of State Condoleezza Rice declared recently. In calling world leaders together for last week's conference in Annapolis, Md., the Bush administration made it clear it has its own approach.

But the administration's insistence on a limited U.S. role is one of the reasons behind widespread skepticism about the likelihood of the talks resulting in a peace agreement and an independent Palestinian state by the end of Bush's term. Most European and Arab diplomats believe a more activist U.S. stance is essential to progress.

At the same time, many diplomats and analysts acknowledge some advantages to a more circumscribed U.S. role, particularly in the opening stages of talks. But staying aloof becomes harder and harder, they say, as talks bog down, which is likely to happen.

A limited U.S. role puts the burden on the two sides to take responsibility for dealing with each other, rather than allowing each to negotiate with the United States, experts said. In past efforts, Palestinian and Israeli representatives have tailored their offers to please the American intermediaries, focusing less on compromises that might satisfy the opposition.

Saeb Erekat, the chief Palestinian negotiator, said that in his view the central American role has sometimes allowed the two sides to get off easy and avoid grappling with the painful issues.

Israelis and Palestinians are "masters" at waiting and find it easier to avoid tough choices when a third party is involved, Erekat said in an appearance sponsored by the Brookings Institution's Saban Center.

"It's time for decisions -- Palestinian and Israeli, our decisions," Erekat said. "Nobody can make them for us."

Importantly, Bush's hands-off approach gives political cover to Israeli Prime Minister Ehud Olmert from domestic critics. The Israeli right is worried that peace talks will mean U.S. pressure to give ground to the Palestinians. Bush's declaration will reassure them and help Olmert avoid major damage to his political support while the talks get underway, experts said.

But in time, the determination of Bush and Rice to stay close to the sidelines probably will be tested.

For instance, a significant Palestinian attack in Israel could lead to pressure to suspend talks, a possibility acknowledged last week by Olmert's chief spokeswoman, Miri Eisin. In such an event, the Bush administration would have to step up to keep talks on track.

U.S. officials also could come under immense pressure to intervene if the two sides hit an impasse over the core issues: Israeli settlements in the West Bank, control of Jerusalem, the status of Palestinian refugees, and the borders of a Palestinian state.

"I'm not sure the Americans are going to be able to stay out of the middle for very long," said Samuel Lewis, who was U.S. ambassador to Israel for eight years under Presidents Carter and Reagan. "Moments of truth may come on each one of the major issues."

Practically, having the United States more squarely in the middle of negotiations can be helpful, experts said. Such a role can help provide diplomatic "cover" for sacrifices by Israelis and Palestinians.

In the past, Israeli and Palestinian leaders have been able to explain difficult compromises to skeptical constituents by saying they had to yield ground because of strong pressure from Washington.

An active U.S. presence also can prevent squabbling or domestic political considerations from overshadowing the talks, said Ghaith Omari, a former senior advisor to Palestinian Authority President Mahmoud Abbas.

"Without a heavy U.S. involvement, the process will not move forward," he said.

But even without an eventual deal, the administration stands to net political gains from the first Mideast peace negotiations in seven years.

An original impetus behind Rice's yearlong effort to resume Mideast negotiations was to strengthen the coalition of countries concerned about the growing influence of Iran and weaken Tehran's appeal in the region.

Iran has capitalized on the resentment of ordinary Arabs at the plight of the Palestinians. A peace effort could quiet some of the resentment and prevent Tehran from exploiting the issue, administration officials believe.

Peace talks also could help the Bush administration by offering a more positive look to American activities in a region dominated by U.S. invasions and counter-terrorism campaigns.

By accentuating U.S. diplomacy, the initiative could "change the narrative of the administration's foreign policy in the region," said Richard N. Haass, a senior State Department official during Bush's first term and now president of the Council on Foreign Relations.

European diplomats believe that although Rice is realistic about the limited chances for a breakthrough, she may hope to lay the foundation for a later peace deal for which she and the administration would win credit from historians.