The US Senate will vote within hours this Thursday evening on a second and likely final cash injection for the taxpayer-funded CARS (‘cash for clunkers’) programme which ran through its original $1bn allocation in a week.

Democrat Senator Debbie Stabenow of Michigan told Bloomberg Television the $2bn expected to be approved tonight would “probably be the last infusion of dollars”, adding that the incentive scheme to spur buyers to junk old cars for more fuel efficient models had been “incredibly successful”.

“It really goes right to the heart of creating demand,” she said, “helping people that need to buy a new vehicle to be able to do that. We know that if we are getting the inventory off of the dealership lots… then you have to make more automobiles and that puts people back to work.”

Stabenow said officials at steel and aluminium industries and other suppliers had indicated the clunkers scheme would have a “very positive effect on them as well”.

She said the seven amendments Senate Republicans had added to the clunkers bill ahead of the vote there tonight would have to be discarded as House representatives, to which the modified bill would have to return for another vote, had already left for their summer break.

“The only option if we want to continue cash for clunkers is to pass the bill that the House passed.”

Stabenow said Senate Democrats agreed to allow Republican senators to insert amendments as a way to stop them from blocking the bill but said it was “very important” none of those actually passed tonight.

The auto state senator added she expected the clunkers vote to start some time after 15:00EST (20:00BST) and that there would be about three hours of votes on the amendments ahead of the final vote on the bill – the senate’s last task this session.