On Thursday, after months of intensive but low-key diplomacy, the United Nations special envoy for Syria, Geir Pedersen, plans to bring 150 Syrians to Geneva. There, they will begin work on a constitutional committee intended to shift attention from the battlefield to what happens when, sooner or later, the fighting in their country stops.

Mr. Pedersen’s immediate goals are modest. He does not expect to achieve a peace, he said in an interview, but reforming Syria’s Constitution, could serve as “a door opener to a political process.”

“We all understand that the constitutional committee itself will not bring a solution to the conflict,” he said.

The Geneva talks are meant to be a first step under a United Nations Security Council mandate that calls for a nationwide cease-fire and elections under United Nations supervision.

A senior State Department official said Monday that the United States and other nations had several points of leverage to try to get Mr. Assad to work on a political settlement. The official, who briefed reporters on the condition of anonymity, said that could include keeping reconstruction assistance from Mr. Assad’s government, barring Syria’s re-entry into the Arab League and refusing to restore diplomatic ties with Damascus.