WASHINGTON (AP) -- The Senate is poised to pump $2 billion more into the popular "cash-for-clunkers" program after agreeing to give shoppers until Labor Day to make a deal on more energy-efficient models.
The White House has estimated that tripling the $1 billion program could pay for 500,000 more new-car sales, giving automakers a late-summer boost after months of ragged business. The Obama administration has said the program would go broke by Friday without Congress' approval of the extension.
Senate Majority Leader Harry Reid said Democrats and Republicans had agreed to vote on the plan later Thursday after the formality of considering potential changes to the House-passed version of the bill. None of those amendments is expected to pass.
"We all know that if we change the bill, it will die," Reid, D-Nev., told reporters on Thursday. "We are going to do everything we can to stop that."
Democrats and the two independents who caucus with them hold 60 seats, enough to kill an effort to block the bill - if everyone shows up to vote. At least one senator in that supermajority was not expected to attend Thursday's session, Sen. Edward Kennedy of Massachusetts, who is battling brain cancer. A few Republicans, however, were expected to side with the Democrats.
Senate approval of the House version would send the legislation to the White House for President Barack Obama's signature and assure consumers there will be no interruption in the program that provides up to $4,500 in rebates and helped rescue car dealerships from lagging sales.
The proposed changes that will receive an airing include placing an income limit on those benefiting from the vouchers, terminating the Troubled Asset Relief Program and requiring the government to sell off its shares in Michigan automakers General Motors Co. and Chrysler Group LLC.
Sen. Tom Harkin, D-Iowa, for example, wants the vouchers limited to individuals earning less than $50,000 a year or joint filers earning less than $75,000.
As the bill stands, Microsoft founder Bill Gates can get $4,500 to buy a new car, Harkin said Thursday. "You have to ask," Harkin said, "is this a wise way to spend limited amounts of money?"
Any Senate changes to the bill would require another vote in the House, something that couldn't take place until the House returns in September from a monthlong recess. The Senate is taking its break following votes on the car incentives and the confirmation of Supreme Court nominee Sonia Sotomayor.
Republican opponents have conceded they are unable to force all of the changes they want or to block the House version of the bill. But they still grumbled about more government handouts to the private sector.
Sen. John Thune, R-S.D., called the bill an example of "Congress choosing winners and losers among industries."
The government said Wednesday that more than $775 million of the $1 billion fund had been spent, accounting for nearly 185,000 new vehicles sold. Administration officials estimate the extra funding will last into Labor Day.
Car companies credit the clunkers program with driving up sales. Most consumers are buying smaller, more fuel-efficient vehicles through the program, according to a list of the top-10 selling cars released by the government.
Among manufacturers, General Motors Co. had the largest share, accounting for 18.7 percent of new sales; followed by Toyota Motor Corp., with 17.9 percent; and Ford Motor Co., with 16 percent. Detroit automakers represented 45.3 percent of the total sales while Japan's Toyota, Honda Motor Co. and Nissan Motor Co. accounted for 36.5 percent.
The Toyota Corolla is the top-selling vehicle on the list, followed by the Ford Focus, Honda Civic, Toyota Prius and the Toyota Camry. There is one SUV on the list, the Ford Escape, which also comes in a hybrid model that can get up to 32 miles per gallon. Six of the top-10 selling vehicles are built by foreign manufacturers, but most are built in North America.
The prospect of extending the clunker program is causing automakers to rethink their production schedules and perhaps bring back laid-off workers.
GM's manufacturing team was working on a production increase Thursday morning, Tom Stephens, vice chairman of product development, said in an interview.
GM has had spot shortages of compact and midsize cars, which have been popular with people trading in clunkers, Stephens said. The company also reported an increase in sales of the Chevrolet HHR small sport utility.
"Consumer confidence is really what you need here," Stephens said. "It's hard for them if they don't know if they have a job or a for-sure paycheck to go out and make a major purchase, so I think this is kind of jump-starting some things."
Hyundai Motor Co. already has added a day of production at its Montgomery, Ala., factory, while Ford Motor Co. is considering a production increase.
AP Auto Writer Tom Krisher contributed from Traverse City, Mich.