Who's Buying This Election? Close to Half the Money Fueling Outside Ads Comes From Undisclosed Donors
Of the nearly $300 million spent by outside groups so  far in attempts to influence the election, the public remains  completely in the dark about who’s behind 42 percent of these  expenditures, an Election Day analysis by the Center for Responsive Politics indicates.
 Some groups spending big bucks  in advance of the election -- namely nonprofits that classified as  501(c) groups under the U.S. tax code -- are not required by law to  disclose their donors. And their political investments this year have  proliferated, with some of these groups taking advantage of the new  campaign finance landscape that no longer prohibits their use of  corporate cash in the final stretch of the election. 
 At the federal level, more than $123 million has been donated by  anonymous sources to nonprofit organizations that have run television  and radio advertisements, sent out direct mailers and bought up Internet  ad space ahead of today’s election.
 Many of these nonprofits are affiliated with explicitly political  groups registered under section 527 of U.S. tax code -- political action  committees, “super PACs” or other 527 organizations, entities that must  disclose their donors. Oftentimes, one organization’s different legal  entities use the same name, so tracking where the money is coming from  -- and which one of those legal entities is making the expenditures --  is all the more difficult.
 Some of those 501(c) groups include Planned Parenthood, Equality  California and American Rights at Work on the left and Crossroads  Grassroots Policy Strategies, the National Rifle Association and  Americans for Prosperity on the right.
 The U.S. Chamber of Commerce,  a 501(c)6 business association that isn’t required to disclose its  donors, ranks as the top outside-spending group that is not a party  committee, such as the Democratic National Committee or Republican  National Committee. The Chamber has spent $35 million this election  cycle on “electioneering communications,” targeted broadcast messages  that include a visual or audio reference to federal candidates but don’t  expressly advocate for or against those candidates.
 The next three of the top five outside spenders are all  conservative groups that share office space, operatives and a similar  lineage.
 American Action Network, a 501(c)4 organization headed by former Sen. Norm Coleman  (R-Minn.), has spent $26.6 million on a combination of general  electioneering communications and “independent expenditures” that  expressly advocate for or against federal candidates.
 American Crossroads, a 527-organization-turned-“Super PAC” that promoted to donors by
 Karl Rove, has spent $21.6 on independent expenditures, mostly  advocating against Democrats. All of its donors -- many of which are  corporations or billionaires -- have been disclosed, as OpenSecrets Blog has previously reported.
 American Crossroads’ sister 501(c)4 organization is not required to disclose its donors. This group, Crossroads Grassroots Policy Strategies, has spent $17.1 million on independent expenditures and electioneering communications.
 The only liberal-aligned group in the top five outside spenders is the Service Employees International Union. The SEIU has spent more than $15.7 million on ads and other communications as it works to elect Democrats.
 Overall, for every $1 a liberal group has spent on these expenditures, a conservative group has spent $2, the Center’s research shows.