In the wake of General Motors filing for bankruptcy and Chrysler emerging from it, the Senate is poised to approve a "cash for clunkers" program as early as Wednesday.

Sens. Debbie Stabenow, D-Mich., and Sam Brownback, R-Kan., introduced an amendment Tuesday that would set up a program that allows consumers with older, less fuel efficient vehicles to trade in their "clunker" for a voucher worth up to $4,500 toward the purchase of a new car that must get at least 22 miles per gallon or an SUV or pickup that gets at least 18 mpg -- clearly a focus on U.S. manufacturers.

The one-year program is expected to help sell 1 million vehicles, according to Stabenow and Brownback.

The definition of "clunker" is a vehicle that gets 18 mpg or less, and the voucher size varies. Owners who purchase a new passenger car that gets at least 4 mpg higher than their old "clunker" get a $3,500 voucher. If the mileage difference is more than 10 mpg, the consumer gets the full $4,500. 

Buyers of small trucks and SUV's fare better. If the new vehicle gets at least 2 mpg more than the "clunker," a $3,500 voucher is issued; for new trucks or SUV's getting more than 2 mpg, the new car owner gets $4,500.

The trickier problem of navigating the House could be solved soon, a senior Senate Democratic leadership aide told FOX News  It appeared, according to the source, that House leaders have agreed to accept the Senate bill, if it passes.

The Stabenow-Brownback amendment would be attached to a larger bill that grants the Food and Drug Administration new authority to regulate tobacco products. Final passage of this bill is expected to come likely next week, the aide said.