The prevailing narrative among the pundits, including more than a few experienced Middle East hands, is that while the Israelis and Palestinians may have sent their negotiators to Washington to placate Mr. Kerry, neither side appears remotely prepared to make the hard calls needed to cement a lasting peace.

Some experts argue that it may be risky even to try.

“The existence of talks can have a calming effect while they continue, and if they continue for several months can get us through the U.N. General Assembly without bitter Israeli-Palestinian confrontations,” said Elliott Abrams, who was a senior official on President George W. Bush’s National Security Council.

“But I see no realistic possibility that a final status agreement can be reached now,” Mr. Abrams said. “I just hope there are two State Department teams: one to work on the talks, and the other to start planning for what to do when they fail. We should not only try to avoid a crash landing, but see if the talks can be used to advance Israeli-Palestinian economic and security cooperation.”

In recent weeks, Mr. Kerry and his aides have outlined several basic arguments for why his efforts might bear fruit. Perhaps the most important one, which Mr. Kerry advanced almost the moment he was picked for the State Department post, is that the United States does not have the luxury of staying on the sidelines.

With the Palestinians poised to take their claim for statehood to the International Criminal Court and United Nations bodies, American officials say the two sides were facing a downward spiral in which the Israelis would respond by cutting off financing to the Palestinian territories and European nations might curtail their investment in Israel, further isolating the Israelis.