A Project of The Annenberg Public Policy Center

League of Conservation Voters

An environmental group launched in 1969 that targets a “Dirty Dozen” list of politicians for defeat.

Independence USA

A left-leaning super PAC founded and financed by former New York City Mayor Michael Bloomberg.

American Crossroads/Crossroads GPS

Affiliated Republican advocacy groups formed with the help of Ed Gillespie, former chairman of the Republican National Committee, and Karl Rove, an adviser to President George W. Bush.

Congressional Leadership Fund

A super PAC focused on maintaining and expanding the Republican majority in the House of Representatives.

Americans for Prosperity

A major force behind the tea party movement, this conservative/libertarian group was founded by billionaire businessman David Koch.