Paul Blumenthal for HuffPo:

“First of all, what I give isn’t ‘dark.’ What I give politically, that’s all reported,” he said. “It’s either to PACs or to candidates. And what I give to my foundations is all public information.”

This statement, however, is an almost impossible pill to swallow. Koch has indeed made publicly disclosed contributions of more than $580,000 to federal political parties, candidates and political action committees since 1997, according to Federal Election Commission records. In 2014, he also contributed $5 million to his Freedom Partners Action Fund super PAC, which must disclose its donors.

But Koch and his brother are best known for the network of nonprofits they operate and raise money for that do not disclose their donors.

These include grant distribution hubs like Freedom Partners Chamber of Commerce, Center to Protect Patient Rights and TC4 Trust. The three groups have distributed more than $450 million in grants to other nonprofits, many of them active in elections, since 2009, according to nonprofit tax forms compiled by the Center for Responsive Politics. Freedom Partners Chamber of Commerce, a 501(c)(6) trade association that hosts the Koch brothers’ annual donor summit, is currently the only hub that remains operational and is still affiliated with the Koch brothers.

Nonprofit tax forms also reveal that the large majority of these grants went to Koch-connected groups that have spent money on elections, like Americans for Prosperity, American Energy Alliance, Concerned Veterans for America, Generation Opportunity and The LIBRE Initiative. Other major recipients included big election spenders like 60 Plus Association, American Future Fund, Americans for Job Security, Republican Jewish Coalition and the U.S. Chamber of Commerce.