President Obama starts his much anticipated Middle East tour on Wednesday in Saudi Arabia, where he is expected to press the Arab nations to offer a gesture to the Israelis to entice them to accelerate the peace process.

But when he meets in Riyadh, the Saudi capital, with King Abdullah, he should be prepared for a polite but firm refusal, Saudi officials and political experts say. The Arab countries, they say, believe they have already made their best offer and that it is now up to Israel to make a gesture, perhaps by dismantling settlements in the West Bank or committing to a two-state solution.

“What do you expect the Arabs to give without getting anything in advance, if Israel is still hesitating to accept the idea of two states in itself?” said Mohammad Abdullah al-Zulfa, a historian and member of the Saudi Shura Council, which serves as an advisory panel in place of a parliament.

While not dismissing the possibility of some movement on the peace process, the Saudis say the Arab world made substantial concessions in the Arab Peace Initiative, which was endorsed by a 22-nation coalition during an Arab League summit in Beirut, Lebanon, in 2002. That proposal offered full recognition of Israel in exchange for Israel’s withdrawing to its 1967 borders and agreeing to a “just settlement” to the issue of the Palestinian refugees.

The Saudis are concerned about the potential threat to the coalition should one nation make further concessions on its own. That, they say, could provide the less committed countries a rationale for abandoning the peace initiative, according to officials and regional analysts.

“Any unilateral decision from any Arab head of state will shred the Arab world and tear its ranks, because there will always be those who oppose and those who support,” said Anwar Majid Eshki, director of the Middle East Center for Strategic and Legal Studies in Riyadh.

President Obama has said he is traveling to the Middle East to push for settling the Arab-Israeli conflict and to improve the image of the United States in the Muslim world. There are likely to be other issues discussed as well, including efforts to curtail Iranian influence in the region and the price and supply of oil.

After visiting Saudi Arabia, President Obama is to arrive in Cairo, where he is scheduled to meet with President Hosni Mubarak of Egypt, give a much anticipated speech from the domed hall at Cairo University and visit the Great Pyramids of Giza and the historic Sultan Hassan Mosque.

Before leaving Washington, Mr. Obama signaled that while he would mention American concerns about human rights in Egypt, he would not challenge Mr. Mubarak too sharply, calling him a “force for stability and good” in the Middle East.

In an interview with the BBC released by the White House on Tuesday, Mr. Obama said he did not regard Mr. Mubarak as an authoritarian leader. “No, I tend not to use labels for folks,” Mr. Obama said.

The president noted that there had been criticism “of the manner in which politics operates in Egypt,” but he also said that Mr. Mubarak had been “a stalwart ally, in many respects, to the United States.”

Officials in Saudi Arabia and Egypt said that Mr. Obama had already made progress on his Middle East agenda, having restored some confidence that the United States is interested in and serious about pushing for a Middle East settlement.

With that reserve of good will, any proposal the president offers will be considered, officials said. But response to it will also be limited by what the leadership here sees as its bottom line: they cannot grant concessions without first gaining some, and all decisions must be agreed to by all members of the Arab League.

“In our estimation we will judge everything by the degree of Israeli commitment, and measures that are taken,” said Ambassador Hossam Zaki, a spokesman for the Egyptian Foreign Ministry. “In other words, if the Israeli side remains evasive and does not commit to any substantial move to redress the situation and put it on the right track, it is unlikely to see that Arab countries are going to be responsive to any request of gestures.”

A Saudi official who spoke on the condition of anonymity, because he was not authorized to discuss details of the presidential visit, said that Arab nations might be willing to accept certain incentives to expedite the peace process, but only if they occur simultaneously with Israeli action.

“It depends on what the Israelis give,” the official said. “Israelis say, ‘We opened a passage.’ Come on, you open a passage, you close a passage. That is not one of the issues. Let’s deal with the major issues.”

It is hard to overstate how much excitement President Obama’s visit here has generated. People across the crowded metropolis of Cairo are marveling at how much sprucing up the government has done, from paving over the road in front of Cairo University to painting light poles and bridges to planting trees and bushes around the Citadel.

Officials, political analysts and residents said there was an atmosphere of what might be described as skeptical optimism. No one here is predicting a breakthrough in the Arab-Israeli conflict; but with the president at least talking about criticizing Israel over its settlement policy and with his personal popularity relatively high, there is a hint of optimism.

“I think we should hear something positive from President Obama,” said Ahmed Kattaan, the Saudi ambassador to the Arab League. “I think he is going in the right way now.”