Aug. 2 (Bloomberg) -- The future of the U.S. “cash for clunkers” program depends on the Senate backing a $2 billion infusion this week, with at least one Republican saying he was going to try to block the effort.

“We’ve got to slow this thing down,” Senator Jim DeMint, a South Carolina Republican, said on “Fox News Sunday.”

The House voted 316-109 on July 31 for an emergency measure adding $2 billion to the program aimed at reviving U.S. auto sales, after a burst of demand exhausted most of the initial $1 billion in less than a week.

Transportation Secretary Ray LaHood said in a C-SPAN interview Sunday he expects the current $1 billion in funding to be gone by the end of the weekend. The administration will continue the program until the Senate acts, and dealers will be reimbursed for deals in the pipeline, he said. The government will make a “good-faith effort” for transactions beginning tomorrow, he said.

DeMint said he opposes the program because “we’re helping auto dealers while there are thousands of other small businesses that aren’t getting help.”

Help for McCain

“We’re definitely going to debate it,” he said. “I heard that John McCain is going to stand up and try to stop it, and I’m going to work with him every way I can,” he said.

Senator McCain of Arizona is among Republicans who indicated they will vote against the measure. McCain has been “opposed to cash for clunkers from the beginning” because of the cost to taxpayers, Brooke Buchanan, his spokeswoman, said Friday. In an e-mailed statement yesterday, she said that while McCain will vote against the $2 billion, he won’t try to block Senate consideration of the measure.

“Any extension of the ‘cash for clunkers’ program must go further in advancing the goals of better fuel efficiency and greater emissions reductions,” Senators Dianne Feinstein, a California Democrat, and Susan Collins, a Maine Republican, said in a joint statement. “We will not support any bill that does not meet these goals.”

Named the Car Allowance Rebate System, the program provides credits of as much as $4,500 for the purchase of a new car when turning in an older vehicle to be scrapped. Lawmakers had expected the first $1 billion to generate about 250,000 vehicle sales and last until about Nov. 1.

Caution Advised

The National Automobile Dealers Association said last week that its members should be cautious about signing more deals with customers under the program. Dealers provide buyers the discount they qualify for under the program and then submit paperwork for reimbursement to the federal government.

Demand kindled by the clunkers program may push U.S. auto sales to a 2009 high in July, possibly signaling a bottom in the market’s worst slump since at least 1976. Sales have run at a seasonally adjusted annual rate of fewer than 10 million units since December. That pace trails last year’s total of 13.2 million and the 16.8 million average from 2000 through 2007.

The program was designed to subsidize more new-vehicle purchases in the effort to revive dealerships and automakers while getting older, less fuel-efficient vehicles off the road. It has been advertised by automakers in print and on television.

Senators are unlikely to make changes in the end because they “will be under intense political pressure to fix the program before they leave” next week for their August recess, said K. Whitney Stanco, an analyst for Concept Capital, a financial research firm in Washington.

To contact the reporters on this story: Angela Greiling Keane in Washington at agreilingkea@bloomberg.net; Holly Rosenkrantz in Washington at hrosenkrantz@bloomberg.net.

Last Updated: August 2, 2009 13:15 EDT