“Dark money” is a term used to describe political spending by groups that are not required to disclose their donors. Most often it refers to groups designated by the IRS as 501(c) organizations — businesses, issue advocacy groups, unions, civic and trade organizations (including many nonprofits) which are not allowed to directly contribute to a candidate or campaign, but are allowed to spend money to educate or advocate about issues related to politics or to provide information about where candidates stand on certain issues. (Transparency USA is a 501(c)(3) organization because we provide information and education to the public concerning the money in politics.)

It is a common practice for former members of the legislature, following their retirement or defeat at the ballot box by voters, to return immediately to the Capitol as lobbyists. Such an immediate return ensures that the influence the former member built up while in office is still valuable. Most of the players are still around, and the former members are now part of the even-more-powerful Capitol lobby crowd.