Unless the Senate approves $2 billion in additional funding, the popular Cash for Clunkers program may be shut down by mid-week. On Sunday the Obama administration said they were optimistic that the Senate would approve the additional funding needed to extend the program, however, also warned that it would be suspended midweek without new funding.

The House of Representatives on Friday authorized an additional $2 billion for the program, after all of the initial $1 billion was used up just one week after the program began on July 24.

Transportation Secretary Ray LaHood said:

"This has been a wildly popular program and given new life to auto dealers. This has worked very, very well."

LaHood added that the administration anticipates that the Senate will follow the House's lead and approve the additional funding. Questions began to emerge Sunday, however, about a possible Republican attempt to block the extension.

It is possible though that some opinions may be swayed today as the "Big 3" automakers report their monthly US sales. Industry analysts expect to see a bump in the number of vehicles sold, due mostly to the Cash for Clunkers program.

Dealers are unsure of how to proceed, and the program's uncertain future has led the National Automobile Dealers Association to advise its members to play it safe and not close any more deals until the fate of the program was finalized.

Under the Cash for Clunkers program, vehicles purchased after July 1 are eligible for refund vouchers worth $3500 to $4500 on traded-in gas guzzlers. To be eligible, the trade-in vehicle has to get a combined city and highway fuel economy rating of 18 miles per gallon or less. The program also requires dealers to render traded-in vehicles permanently inoperable before even applying for their rebates. However that stipulation has been amended, and dealers can now wait until receiving the rebate before disabling the vehicle.