Mr. Kerry said that the investments under the plan would be made in the areas of tourism, light manufacturing, agriculture, construction, energy and technology. The idea would be to give the Palestinians an incentive to negotiate and to ensure that a Palestinian state in the West Bank would be viable.

Neither Mr. Kerry nor his aides provided any details on what specific projects were envisioned, who might invest and what modifications might be required in Israeli restrictions on the West Bank for the plan to work.

Reporters traveling with Mr. Kerry were told to direct their questions to the “quartet,” a Middle East peacemaking group whose experts devised much of the plan. Former Prime Minister Tony Blair of Britain serves as the Middle East envoy for the group, which is made up of the United States, Russia, the European Union and the United Nations.

A statement issued Sunday night by Mr. Blair’s office said the economic initiative was intended to parallel the political process and not replace it. Officials from the quartet are still consulting experts on the Palestinian economy and will provide details about specific options “in due course,” the statement said.

As Mr. Kerry has tried to set the stage for negotiations, Palestinian officials said he had asked them to hold off on seeking membership in international forums to underscore their claim to statehood, a request they said they would comply with only until June 7. The Israeli government, meanwhile, has quietly refrained from issuing bids for construction in West Bank settlements or from announcing major building projects.