In an analysis of 2011 and 2012 tax filings, The Washington Post and the Center for Responsive Politics found that a coalition of nonprofit groups backed by a donor network organized by the billionaire industrialists Charles and David Koch raised more than $400 million in the last election cycle. Much of the money was distributed to a maze of limited-liability companies affiliated with the nonprofits, which used some of their resources to turn out conservative voters and run ads against President Obama and congressional Democrats. Read related story.

Source: Robert Maguire with the Center for Responsive Politics | Matea Gold and Cristina Rivero/The Washington Post