WASHINGTON  – President Barack Obama’s chief spokesman says the popular cash for clunkers rebate program may not survive beyond Friday if the Senate doesn’t provide a $2 billion cash infusion.

The program ran out of money last week. The House voted to provide another $2 billion before leaving for summer break last Friday. But the Senate must also vote before its August vacation starts Friday.

White House spokesman Robert Gibbs says the rebate program is up and running. He says anyone who wants to trade in a less fuel-efficient vehicle for a higher-mileage one should do so.

But if the Senate fails to act by Friday, Gibbs says it’s unlikely the program will be available next weekend and beyond.