WASHINGTON  President-elect Barack Obama and leaders in Congress are fashioning a plan to pour billions of dollars into a jobs program to jolt the economy and lay the groundwork for a more energy-efficient one.

The details and cost of the so-called green-jobs program are still unclear, but a senior Obama aide, speaking on the condition of anonymity to discuss a work in progress, said it would probably include the weatherizing of hundreds of thousands of homes, the installation of “smart meters” to monitor and reduce home energy use, and billions of dollars in grants to state and local governments for mass transit and infrastructure projects.

The green component of the much larger stimulus plan would cost at least $15 billion a year, and perhaps considerably more, depending on how the projects were defined, aides working on the package said.

During the campaign, Mr. Obama supported a measure to address global warming by capping carbon emissions while allowing companies to buy and trade pollution permits. He said he would devote $150 billion of the revenue from the sale of those permits over 10 years to energy efficiency and alternative energy projects to wean the nation from fuels that are the main causes of the heating the atmosphere.