A key congressional ally of President George Bush said Prime Minister Ariel Sharon's plan for an Israeli unilateral withdrawal could be the first step toward the establishment of an Arab-administered trusteeship of the West Bank and Gaza Strip.

Senate Foreign Relations Committee chairman Richard Lugar called on Arab states and the West to support Sharon's plan for a unilateral withdrawal from the Gaza Strip and portions of the West Bank. Lugar, a Republican from Indiana, said the plan could result in an Arab-administered trusteeship in the areas evacuated by Israel until the restoration of stability required for the establishment of a sovereign Palestinian state.

"We must recognize that Prime Minister Sharon's unilateral disengagement has created an opportunity that we should seize to generate new attitudes and approaches to ending the violence," Lugar told the Washington-based Brookings Institution on Monday. "His decision to evacuate unilaterally almost all settlements in Gaza and a number in the West Bank, once unthinkable by any Israeli leader, is being accepted by most within Israel."

The speech represented the strongest endorsement of Sharon's plan within Congress and a signal that the House and Senate could approve some of the U.S. financial and political guarantees sought by the Israeli prime minister. Congressional sources said Lugar's speech marked a growing recognition within the Bush administration that an Israeli withdrawal could represent a U.S. foreign policy achievement in the Middle East prior to the presidential elections in 2004.

"We, obviously, take anything that the chairman of the Senate Foreign Relations Committee puts forward very seriously," State Department spokesman Richard Boucher said on Tuesday. "I'm sure we'll look at it carefully. How much those ideas might be integrated into what we're doing or adopted, I don't know."

On Thursday, three envoys of the Bush administration were scheduled to arrive in Israel and meet Sharon. U.S. Assistant Secretary of State William Burns and two National Security Council senior officials were in Brussels on Wednesday for a discussion of Sharon's plan with the European Union. From Jerusalem, the three U.S. envoys were scheduled to proceed to Amman and Cairo.

A senior administration official said the United States would not seek the deployment of a peacekeeping force, including one from NATO, in any of the areas evacuated by Israel. The official said such a force could not replace U.S. diplomatic efforts to find a Palestinian partner willing to restore control and renew peace negotiations with Israel.

"I don't think that a NATO peacekeeping role, or not, is the answer to that," the official said on Tuesday. "If we're at a stage where there is a settlement, or there is an agreement of some kind, [or that] we've found the Palestinian interlocutor who's willing to work for peace, then we could look at the question: What kind of support would that require, and would a NATO role be appropriate?"

For his part, Lugar said the United States has been urging Egypt and Jordan to become part of any post-Israeli security regime in the Gaza Strip.

The senator, however, also called on the administration to encourage what he termed other moderate Arab countries to assume significant responsibility for rehabilitating and restructuring the Palestinian Authority.

"There is concern that the Palestinian Authority is so weak and fragmented that upon an Israeli departure, a radical group such as Hamas could emerge as the de facto rulers," Lugar said. "That's why the administration is promoting the active involvement of Egypt and Jordan in any security arrangement in Gaza. But we can and must go further."

[On Tuesday, Sharon won the endorsement of his Likud Party for a referendum among its 200,000 members regarding the withdrawal plan. Sharon's aides said such a vote, meant to bind Likud Cabinet ministers, could be held in May.]

Lugar, regarded as close to Secretary of State Colin Powell, linked the withdrawal from the Gaza Strip and parts of the West Bank to the construction of the Israeli security fence. He said a combination of the Israeli withdrawal and the fence will reduce Palestinian capabilities to attack Israelis and result in the removal of Israeli military checkpoints.

The senator stressed that his proposal for a trusteeship in the West Bank and Gaza Strip has not been formally endorsed by the Bush administration. But he said such an arrangement would ensure the restoration of Palestinian order and security with on-the-ground assistance from Arab states.

"This trusteeship would provide enhanced security for both Palestinians and Israelis," Lugar said. "It could restructure the Palestinian security services, and lead a reform of the Palestinians' failed institutions. It would turn back sovereignty at the appropriate time. Why shouldn't this trusteeship be managed by Arab nations? This would give them a role in what they themselves claim is at the core of many of their own problems."

Bush has scheduled a meeting with Sharon on April 14 in the White House. A White House official said the meeting would not be postponed amid a recommendation by Israel's state prosecutor for Sharon's indictment on bribery charges.

"That's an internal matter for Israel," White House spokesman Scott McClellan said.