The State Department late last month issued a formal diplomatic message to more than 70 countries urging them to oppose any unilateral moves by the Palestinians at the United Nations. The message, delivered by American ambassadors to their diplomatic counterparts in those countries, argued that a vote would destabilize the region and undermine peace efforts, though those are, at least for now, moribund.

Two administration officials said that the intent of the message was to narrow the majority the Palestinians are expected to have in the General Assembly. They said that and the new peace proposal — to be issued in a statement by the Quartet, the diplomatic group focused on the Middle East comprising the United States, Russia, the European Union and the United Nations — could persuade potential supporters to step back from a vote on recognition, and thus force Mr. Abbas to have second thoughts.

“The fact is there are countries who would choose not to do that vote if there was an alternative,” the first senior administration official said.

In essence, the administration is trying to translate the broad principles Mr. Obama outlined in May into a concrete road map for talks that would succeed where past efforts have failed: satisfy Israel, give the Palestinians an alternative to going to the United Nations and win the endorsement of the Europeans.

Diplomats are laboring to formulate language that would bridge stubborn differences over how to treat Jewish settlements in the West Bank, and over Israel’s demand for recognition of its status as a Jewish state. A statement by the Quartet would be more than a symbolic gesture. It would outline a series of meetings and actions to resume talks to create a Palestinian state.

The Quartet’s members are divided over the proposal’s terms and continue to negotiate them among themselves, and with the Palestinians and Israelis.

Among the issues still on the table are how explicitly to account for the growing settlements in the West Bank. The question of Israel’s status is also opposed by Russia and viewed warily by some European countries. The Palestinians have never acceded to a formal recognition of Israel as a Jewish state, in deference at least in part to the Palestinians who live in Israel.