These groups, unlike the more commonly known super PACs, are not required to divulge the names of their donors, and much of their spending is unreported, too. Their annual tax filings with the IRS list how much money they have, who their officers are and the recipients of any grants they may have made.
But when they spend their money directly in support of or opposition to a candidate, they must report to the Federal Election Commission. FEC data collected and analyzed by OpenSecrets.org shows that in the 2012 election alone, politically active nonprofits reported spending more than $308 million. Many millions more were likely spent on "issue ads" that escaped reported rules.
