As the Israeli and Palestinian leaders pledged at the peace summit meeting in Washington this week to try to resolve the core issues that have long divided their people and bloodied the land, a growing number of stakeholders here in Israel worried that the two sides were aiming too high.

Some of the nation’s veteran peace process practitioners, along with a range of policy experts and commentators, say that in order to stave off failure, Israel, the Palestinians and their American sponsors should first aim for a partial or interim solution because the gaps between the Israeli and Palestinian positions are too wide.

“We should have a Plan B,” said Oded Eran, director of the Institute for National Security Studies at Tel Aviv University, who led Israel’s negotiating team with the Palestinians from 1999 to 2000.

“If you do not accept the status quo — which I do not — and you cannot obtain an agreement on all the core issues,” Mr. Eran said, “then the alternative is to go for a partial solution while keeping the ultimate political objectives of both sides in mind.”

Support for this interim approach has come from surprising quarters. Yossi Beilin, a former leftist member of Parliament and government minister who was the architect of an unofficial 2003 blueprint for a final peace accord, told reporters in Jerusalem days before the summit meeting that he would advise President Obama “to change the game.”

Concerned that outright failure in the talks could deteriorate into violence, Mr. Beilin said it was preferable to aim for an interim agreement, otherwise “negotiations may be worse than no negotiations.”

The Palestinians reject the idea of partial or interim arrangements, worried that Israel will go no further. One of the transfers of control of West Bank territory agreed upon as part of the Oslo process in the 1990s was never carried out.

Today, Israel maintains full control over 60 percent of the West Bank. In 2005, it withdrew from Gaza unilaterally, and that enclave is now controlled by the Islamic militant group Hamas.

The Palestinian president, Mahmoud Abbas, wants a comprehensive final settlement that will establish a Palestinian state in the West Bank and Gaza, with its capital in East Jerusalem. He also wants a just solution for the Palestinian refugees of the 1948 war and their descendants — one that respects their demand for a right to return to their former homes in what is now Israel.

Israel’s prime minister, Benjamin Netanyahu, says he wants an agreement that will mean the “end of the conflict and of claims on Israel” and that will ensure security and Palestinian recognition of Israel as the national state of the Jewish people. In Washington, he said he was seeking a “historic compromise.”

But those urging a more modest approach argue that Mr. Netanyahu, the most conservative Israeli prime minister to have embarked on final status talks, is unlikely to offer more than his more centrist predecessor, Ehud Olmert. In late 2008, Mr. Olmert proposed an Israeli withdrawal from about 93 percent of the West Bank and compensatory land swaps. Mr. Abbas, who did not accept that offer, is unlikely to settle for less.

To make the idea of an interim deal more palatable to the Palestinians, its proponents emphasize that it must be part of continuing negotiations for a final status accord.

Ehud Yaari, a Lafer fellow at the Washington Institute for Near East Policy and a commentator for Channel 2 news in Israel, argues that Israel should allow the Palestinians to establish a state as quickly as possible, without waiting for a full peace deal.

Mr. Yaari proposes a Palestinian state within provisional borders on about 80 to 90 percent of the West Bank, requiring the removal of at least 50,000 Israeli settlers. He also suggests interim arrangements for some of the other issues, like an administrative role for the Palestinians in East Jerusalem without necessarily resolving the issue of sovereignty, and an early compensation and resettlement package for refugees already living in the territories conquered by Israel in the 1967 war.

Any interim deal should be accompanied by a new document of principles that lays out the broad outlines of a final agreement, Mr. Yaari said, without resolving every issue in detail.

“You have to look at it as a choice between protracted negotiations that may produce a deadlock — and God forbid a bloody one,” Mr. Yaari said, “or an interim approach that would bring about a dramatic change in the lay of the land.”

Mr. Eran, Israel’s former negotiator, suggests transferring as much West Bank land as possible to the Palestinian Authority, while deferring the issue of statehood to a final accord. Last year, Shaul Mofaz, a former defense minister and now a member of Parliament from the centrist Kadima Party, presented a plan for a Palestinian state with temporary borders on 50 to 60 percent of the West Bank, mainly in areas that are already under Palestinian control. It has been dismissed by analysts as not generous enough.

Palestinian leaders publicly reject any kind of incremental approach. Saeb Erekat, the chief Palestinian negotiator, has repeatedly said that after so many rounds of negotiations, it is time for decisions on the endgame.

When asked earlier this week about the possibility of an interim deal, the Palestinian Authority’s prime minister, Salam Fayyad, said: “No, no. The plan is a Palestinian state on all the land occupied in 1967.”

Khalil Shikaki, a prominent Palestinian analyst, said an interim deal could not be the outcome or a goal of negotiations. But as Mr. Fayyad continues with his plan to build the institutions and infrastructure of a future Palestinian state, Mr. Shikaki suggested, Israel could transfer more territory to Palestinian control.

“Then gradually,” he said, “a state in provisional borders is what you will have.”