WASHINGTON — With President Bush’s legacy riding in part on a peace summit scheduled later this year in Annapolis, Md., the parley’s first test will be tomorrow in Jerusalem at a meeting of the Israeli and Palestinian Authority leaders.

The meeting between Prime Minister Olmert and President Abbas will be the first chance for the world to learn of the substance of four prior meetings between the two leaders. Both sides are expected to disclose their formal negotiating positions for the coming Annapolis meeting, scheduled tentatively for the weekend after Thanksgiving.

In anticipation of tomorrow’s meeting, Israel released 57 Palestinian Arab prisoners, while the Foreign Minister Tzipi Livni called on Arab states to refrain from setting conditions on any future deal. Ms. Livni’s message to Arab leaders, who are expected to attend the Annapolis meeting, will be amplified today in a letter from nearly three-quarters of the U.S. Senate to Secretary of State Rice, the architect of the new diplomacy in the Holy Land.

A letter circulating this week from Senator Schumer, a Democrat of New York, and Senator Graham, a Republican of South Carolina, presses Ms. Rice to secure support from Arab states to end their boycott of Israel, recognize the Jewish state, and end terrorism in the run-up to the summit. The letter, to be sent today with the signatures of more than 70 senators, tells Ms. Rice that “without sincere commitment from our allies in the Middle East to be partners in this effort, peace in the region will remain elusive,” according to a copy obtained by The New York Sun.

Ms. Rice has pushed since the Hamas takeover of Gaza in June for comprehensive negotiations between Israel and the Palestinian Authority, which now only exercises nominal control over the West Bank. Even in that area, the remnants of Yasser Arafat’s old Fatah organization now rely in large part on Israel for some basic security, fearing a repeat of the bloody battle the old-line Palestinian Arabs lost in the early summer.

For Ms. Rice, the negotiations are not only a gambit to pry Hamas eventually from Iran’s sphere of influence, they are also a mechanism to keep Sunni authoritarian allies — Egypt, Jordan, and Saudi Arabia — in the American orbit.

Yesterday, Mr. Abbas said he hoped to have a draft agreement on the status of Jerusalem, the return of Palestinian Arab refugees, and final borders before the autumn summit, following a meeting with the King Abdullah of Jordan. Recently, however, Mr. Abbas has hinted that he would not be willing to bend on the right of Palestinian Arabs to return both to Israel and a future Palestinian state, a position successive Israeli governments have rejected as a nonstarter. Israel’s largest newspaper, Ha’aretz, reported yesterday that the Palestinian side would seek an international body to oversee the implementation of any future agreements.

An Israeli diplomat said he was skeptical that any deal could be made, but said that nonetheless Mr. Olmert’s position was to make a good faith effort to deal with Mr. Abbas. “Everyone is concerned that at some point Abbas may go back to Hamas, just as he did in Riyadh,” the diplomat, who requested anonymity, said. “But there is a chance this process can prevent that.”

The diplomat said he believed that the best case scenario for Israel would be to get a statement of principles from Mr. Abbas supported by the Arab states in attendance, which would back away from the right of return and the return to Israel’s pre-1967 borders. Mr. Abbas has agreed to different borders in prior negotiations, including the talks at Taba following the collapse of the second Camp David Accord. On the Arab side, President al-Assad of Syria told the BBC yesterday that his country will not attend the summit unless Israel promises to give up the Golan Heights, territory it won in the Six-Day War in 1967. Meanwhile, high officials in the two countries that have already forged peace agreements with Israel, Jordan and Egypt, say their respective governments will only send a foreign minister to the summit if both Israel and the Palestinian Authority agree to discuss final status issues: refugees, Jerusalem, and borders.

The Saudis have played their cards closest to the vest so far. On the sidelines of the U.N. General Assembly last week, the Saudi foreign minister, Prince Saud al-Faisal, said: “It is not Saudi Arabia that puts conditions, or Saudi Arabia that is going to negotiate. Its presence there, or non-presence, is not the most significant issue.”

An American diplomat told the Sun yesterday that he was optimistic the Saudis would attend but that he was not yet certain.