“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.”