Peter Coors has come under attack for proposing a lowering of the drinking age. The Republican Senate candidate and member of the Coors dynasty has had his support for the proposal questioned by a group behind his GOP primary rival Bob Schaffer in a TV ad.

"Beer executive Pete Coors says we should lower the drinking age so teenagers can drink," says the commercial, which will be released soon by Colorado Conservative Voters. "Makes you wonder what else we should know about Pete Coors. Oh, Pete!"

Coors reiterated his support for lowering the drinking age from 21 to 18 during a debate with Schaffer last month, saying that young people drink anyway and the government has made them criminals.

An earlier ad by the same group criticised Coors for his company's gay-friendly policies.

The two Republicans are battling to succeed retiring GOP Sen. Ben Nighthorse Campbell.