Liberal billionaire Tom Steyer, who founded a super PAC devoted to advancing climate change policies in the United States, refused to disclose his donors moments before claiming to be more transparent than libertarian billionaires Charles and David Koch.

"I definitely can't give you the names of people unless they release it, which we haven't," Steyer, founder of NextGen Climate Action, said on CSPAN's "Newsmakers" program. "We've gotten a handful of people to give pretty significant amounts of money. We have also gone out more broadly."

He then disputed the idea that he is a Democratic analog to the Kochs. "Their policies line up perfectly with their pocket books, and that's not true for us," Steyer said. "What we're doing is we're trying to stand up for ideas and principles that we think are incredibly important but have nothing to do with our incomes or assets." Steyer "made his riches partly in green energy and fossil fuels," as Tim Carney recently noted, but he has divested himself of his green energy profile. It's impossible to verify whether Steyer's donors make money off of green energy policies because he didn't reveal their names.

Steyer then emphasized that his super PAC is more transparent than the Koch brothers. "We're trying to do this in as transparent a way as possible, and we're trying to be completely open in why we're doing it and what we're doing and documenting what we're doing, so that there's no question about something going on here that is secret," he said. "I don't think that's true [of the Kochs]. I think they have not been huge embracers of transparency."