This list includes the organizations that have historically qualified as "heavy hitters" — groups that lobby and spend big, with large sums sent to candidates, parties and leadership PACs. Individuals and organizations have been able to make extremely large donations to outside spending groups in the last few years. While contributions to outside groups like super PACs do not factor into an organization's designation as a "heavy hitter" (a listing of about 150 groups), those numbers are included for the roster below.LINK