But, while Charles and David Koch write checks to the group, they are not directly involved in Americans for Prosperity and there is no evidence Gardner's position on energy subsidies is a result of the Kochs' interests.
Enviro group's ad criticizes Gardner in Colo. race →
"Charles and David Koch are waging a war against anything that protects the environment. I know that sounds absurd, but it's true," he said.
Harry Reid: Koch brothers 'one of the main causes' of climate change →