"I've got confidence we can move the peace process forward," Mr. Bush's said at a meeting with President Gloria Macapagal-Arroyo of the Philippines, adding that the administration's plan, known as the road map, "still stands."

"We're still on the road to peace," he said. "It's just going to be a bumpy road."

Despite the president's hopeful words, some administration officials conceded that little could be done to sustain the delicate momentum of the peace effort if the suicide bombings of the last few days continue.

But the officials also said there was room for Prime Minister Ariel Sharon of Israel, whose visit to Washington this week was deferred because of the latest violence, to improve conditions for Palestinians in the West Bank and Gaza, perhaps by easing some closures and checkpoints, without jeopardizing Israeli security.

Secretary of State Colin L. Powell talked by telephone over the weekend with both Mr. Sharon and Mr. Abbas, the State Department said. 

On Saturday night, while the attacks were going on, Mr. Sharon and Mr. Abbas, who is also known as Abu Mazen, held the first high-level Israeli-Palestinian meeting since the current conflict began 31 months ago.

In Israel, Mr. Sharon was coming under pressure from conservatives in his cabinet to act against Yasir Arafat, the Palestinian leader. But administration officials said it was still American policy to discourage Israel from expelling Mr. Arafat from the West Bank.

State Department officials conceded that a carefully orchestrated timetable for Israeli and Palestinian concessions, proceeding according to a schedule Mr. Powell negotiated when he visited Israel a week ago, was thrown into chaos by the bombing attacks.

Some in the administration say that the attacks were indeed intended to accomplish that objective, perhaps by Mr. Arafat, who has been sidelined as the United States maneuvers to replace him with Mr. Abbas.

Mr. Sharon was to have traveled to Washington by now for a meeting with Mr. Bush at the White House. Administration officials have hinted that Israel had been prepared to ease up on closures, checkpoints, work permits and other onerous restrictions that have badly damaged the Palestinian economy in the West Bank and Gaza.

In addition, Israel had talked of releasing large numbers of Palestinian prisoners and detainees, held since the beginning of the recent wave of suicide bomb attacks.

The administration had hoped that these steps would make it easier for Mr. Abbas, in turn, to start arresting members of militant groups — a step that he and other Palestinians have said they could not carry out without an improvement in living conditions for ordinary Palestinians.

Meanwhile, the administration's strategy of following the step-by-step "road map" — a seven-page document that lays out a timetable for creation of a Palestinian state in three years — has begun to draw increasing fire in the United States and Israel.

Some Israelis are openly disdainful of the timetable, arguing that it requires too many unilateral concessions by Israel in return for amorphous Palestinian promises to end the violence.

Today, two dozen Christian conservatives led by Gary Bauer, a former Republican presidential candidate, urged the Bush administration to "go back to the drawing board" in the Middle East and abandon the current peace plan, saying that it "could lead to a disaster" for Israel and the United States.

On the other side, two former Middle East negotiators said in interviews that the administration's approach could be salvaged only by a more direct intervention in the negotiating process by Mr. Bush himself.

"We've been extremely sensitive about Israel's security needs," said Aaron David Miller, president of Seeds of Peace and a former Middle East specialist under Mr. Bush. "What we need is a full-time Middle East negotiator who is a political figure, who has some Middle East experience and is clearly empowered by the White House."

Martin Indyk, a negotiator under President Bill Clinton, said that because peace efforts were nearly derailed by a spasm of violence, an investment of time and energy by Mr. Bush was needed to restore momentum.

"If the president doesn't intervene now, the road map will be lost," Mr. Indyk said. "We went through these situations time and time and time again. If the president's efforts are focused on getting Abu Mazen to act, and getting Sharon to exercise continued restraint, he can create some momentum here."