Parties and Organizations
From the Political Information.Com site; can search for groups under the categories of "General Party and Policy Organizations," " Political Parties," "Trade Associations," and "Youth Organizations"
Political Advocacy Groups: A Directory of United States Lobbyists
A good starting point to get acquainted with the variety of advocacy groups in the United States
Registered Federal Lobbyist Database
Provided by the Center for Responsive Politics. Allows searching for registered lobbyists by name or interest area. Search results include organizations that hire lobbyists, names of lobbyists, areas of interest, and expenses
VIS Ratings of U.S. Congress - Voter Interest Group Scores
Provides ratings of Congress from a wide range of advocacy groups representing both liberal and conservative view points
