A Palestinian woman helps a child clamber past an Israeli checkpoint on the Ramallah-Jerusalem road. The checkpoints have become a focus of violence that has racked Israel, the West Bank and Gaza for 17 months.

ASHINGTON, Feb. 26 — President Bush thrust himself into the Mideast peace effort today, calling Crown Prince Abdullah of Saudi Arabia and publicly praising his proposal for Israel to withdraw completely from the West Bank and Gaza in return for full normalization of relations with all Arab countries.

The administration also said it was growing more enthusiastic about the prospects of a major Saudi role in the peace effort. Though President Bush's spokesman, Ari Fleischer, characterized the proposal as short of a "breakthrough," he said, "The president praised the crown prince's ideas regarding the full Arab-Israeli normalization once a comprehensive peace agreement has been reached."

Some administration officials said they were less impressed by the content of the Saudi proposal — "It's not a plan, it's a vision," said one — than by the symbolism of having a leading Arab state, the caretaker of Islam's most treasured sites, put forward a plan that would lead to full normalization of relations with Israel.

They cautioned, however, that for decades, successive Israeli governments have rejected calls for a withdrawal to Israel's pre-1967 borders, and they were unsure how Prime Minister Ariel Sharon would view a long-term plan at a time of such rapidly intensifying violence.

Palestinian officials have reacted favorably to the Saudi proposal, which has not been spelled out in detail yet, but Mr. Sharon has made no public comment. After a meeting with the Israeli leader today, Javier Solana, head of foreign and security policy for the European Union, said Mr. Sharon considers the Saudi plan "an interesting idea."

The Palestinian leader, Yasir Arafat, after his meeting today with Mr. Solana on the Saudi concept, announced, "I cannot say no to Solana's suggestion," and dispatched his team to Tel Aviv to discuss ways of lowering the level of violence.

Mr. Solana said he would travel to Saudi Arabia on Wednesday to meet with Prince Abdullah, who first put forward his proposal last week. On Friday, Secretary of State Colin L. Powell initially called the Saudi statement a "minor development," but on Monday he upgraded it to an "important step."

After his return from Asia, Mr. Bush decided there were numerous advantages in embracing the Saudi vision, if not its still-vague specifics.

"This is the first time we've heard any nation in the region talk about full normalization between Arab nations and Israel at the end of the peace process," one senior administration official said. "The president decided that he had to embrace the moment." Other officials and outsiders noted possible benefits for Mr. Bush.

Embracing the Saudi proposal helps the president counter critics who say the administration's hands- off approach to the Middle East for much of its first year only worsened the cycle of violence.

It also helps to change the subject with the Saudis: Mr. Fleischer said today that Mr. Bush and Prince Abdullah never discussed what Saudi Arabia was doing to root out extremists, and never mentioned the investigation of the Sept. 11 hijackers, 15 of whom were raised in Saudi Arabia.

Moreover, with Vice President Dick Cheney scheduled to leave for the Middle East in two weeks to describe the president's reasons for wanting to oust Saddam Hussein in Iraq, an embrace of the Saudi plan could give Mr. Bush some diplomatic leverage by softening Saudi objections to bringing pressure on Mr. Hussein.

American support could also change the tone of the next Arab League summit meeting, scheduled for March 27 in Beirut, Lebanon, when the Saudi proposal is likely to be actively debated. That debate may now drown out criticism of Prime Minister Sharon.

"By legitimating the Saudi initiative, which they had to do, they have changed the context of this coming month," the Mideast scholar Stephen P. Cohen said today.

"It is significant because for all these years, the Arabs have always been clear in spelling out the territory side of `land for peace,' but studiously silent on the peace side of `land for peace.' "

Still, the White House made clear today that it would take a long while for the Saudi proposals to play out.

"It's important to have a vision for what peace should look like at the end of the day," Mr. Fleischer said, "but it's a long time until the end of the day in the Middle East."

He added that the president still believed that it was important for both sides to follow the "Mitchell process" to bring about peace, followed by political and territorial talks. The process is named for its author, the former senator George Mitchell, but it never got beyond its first stages before street violence cut it short. Mr. Mitchell's intention was to halt violence on both sides to build enough mutual confidence to support diplomatic talks between Isarael and the Palestinian Authority.

Mr. Bush's entry onto the state came as American-brokered security talks resumed between Israeli and Palestinian officials in Tel Aviv, with hopes swelling after Saudi Arabia's surprise proposal. The concept, which threw the weight of the Saudi kingdom behind Mr. Arafat at a time when Israel has grounded and humiliated him, heartened the Palestinians, but Palestinian officials are still waiting to hear from Mr. Sharon.

"His reaction was very positive," said a senior lieutenant of Mr. Arafat, Nabil Abu Rdeineh. "We support and welcome the Saudi initiative, and hope it will lead to a breakthrough in the Middle East. The problem is that we hear nothing from Sharon. We need to hear from the Israeli government."

Another senior Palestinian official, Saeb Erekat, said, "We believe that this is the most significant and strategic idea that came from the Arab world since the convening of the Middle East conference in 1991, and I really hope that the American administration will concentrate on the strategic concept of the ideas and not go into the details of any agreement."

But Prime Minister Sharon remained wary, and made no public comment on a plan that revived demands for an Israeli withdrawal far greater than the Israeli right could agree to, and so threatened to put him on the defensive.

After meeting with Mr. Sharon, Mr. Solana said the prime minister "considers it an interesting idea and he would like to know more about the content, and he would like to meet anybody from Saudi Arabia, formally, informally, publicly, discreetly, whatever, to get better information about this initiative."

Despite Mr. Sharon's reserve, centrist members of his cabinet seemed heartened by what commentators described as the first concrete peace signal in 17 months of unmitigated violence.

The defense minister, Binyamin Ben Eliezer, said the plan "should be looked at positively," according to his spokesman. "It has new elements, and it should therefore be encouraged and must not be rejected."

On Monday the Israeli president, Moshe Katzav, said he was prepared to go to Riyadh to discuss the plan, or to welcome Prince Abdullah in Jerusalem. The plan was also being discussed in Paris between the Israeli foreign minister, Shimon Peres, who has welcomed it, and President Jacques Chirac.

From Lebanon came cautious but significant support for the Saudi's proposal. The foreign minister, Mahmud Hammud, said the ideas "grow out of concern for long-held Arab positions and the demand for Israeli withdrawal from all Arab lands."

The importance of Mr. Hammud's statement lay in the fact that Syria holds effective authority over Lebanon.

Syria has made no direct comment on the proposals but the Lebanese response suggested that Damascus could fall in line behind the plan if one of the conditions was the return of the Golan, which Israel occupied in 1967.