GM's top executive is worried about going over the fiscal cliff.

General Motors CEO Dan Akerson has revealed that he is "quite concerned" that the so-called fiscal cliff could have a negative impact on the automaker's United States sales.

"We're watching it very closely," Akerson told The Detroit News.

Unless Washington can agree on a new plan by December 31, expiring tax and spending cuts threaten to push the country over the fiscal cliff. That plunge could send the economy back into a recession, which would have a major impact on all industries, but particularly the new car business.

"The moment certainty is undermined, I think consumer confidence has a tendency to bias downwards and that could affect all companies," Akerson said.

Just in case the country does go over the cliff, Akerson says GM is watching its "inventories extraordinarily closely. It's something we're acutely aware of and watching very carefully."

The White House estimates that the elimination of Bush-era tax cuts could reduce consumers' auto spending by $7 billion.

Through the first 11 months of 2012, GM's sales are up 4 percent to 2,349,984 units.