political-action committee:
(1839)

1. An organization formed by a special-interest group to raise and contribute money to the campaigns of political candidates who seem likely to promote its interests; a group formed by a business, union, or interest group to help raise money for politicians who support the group’s public-policy interests. — Abbr. PAC.  See INTEREST GROUP. [1]

1. A PAC is a committee or other body organized to receive funds in support of candidates for elective office.  The activities of PACs are regulated by federal statute. [2]

     Excerpt from Daniel S. Ward’s “PACs and Congressional Decisions,” in Encyclopedia of the American Legislative System (Joel H. Silbey ed., 1994):

     “To the degree that PACs resemble other organized interest groups, their emergence should not be cause for alarm.  Like the AFL-CIO, the Business Roundtable, the NAACP, the AARP, or Greenpeace, any single political action committee is a collection of individuals (in most cases) with shared interests who have decided to unite in an effort to effect desirable political outcomes.  But what is particularly interesting about PACs-and troubling to some-is the precise nature of their efforts to achieve their goals.  Whereas lobbyists are increasingly limited in what they can provide for legislators in an attempt to influence the policy-making process, the essence of PACs is to provide financial resources to aid election campaigns.  The direct provision of money to lawmakers conjures up images of influence peddling, vote buying, and power brokering, all of which are anathema to representative government.  Thus, although PACs fall under the general rubric of ‘interest groups,’ it is the financial nature of their relationship to members of Congress that makes them subject to close scrutiny.” [3]