Caucus / Congressional Member Organization / CMO / Congressional Staff Organization / CSO (

From the Congressional Glossary – Including Legislative and Budget Terms

Caucus / Congressional Member Organization / CMO / Congressional Staff Organization / CSO


Caucus is from the Algonquian Indian language, where caucus meant “to meet together.” An informal organization of members of the House or the Senate, or both, that exists to discuss issues of mutual concern and possibly to perform legislative research and policy planning for its members. Congressional Caucuses, formally called Congressional Member Organizations, are formed by members of Congress to provide a forum for issues or legislative agendas. A number of caucuses exist in the House and their primary function is to draw attention to issues of importance to their membership. There are regional, political or ideological, ethnic, and economic-based caucuses. Members of both the House and Senate may participate in a CMO, but at least one of the Officers of the CMO must be a member of the House. The participation of senators in a CMO does not impact the scope of authorized CMO activities in any regard.

Members of Congress may form a Congressional Member Organization (CMO) in order to pursue common legislative objectives.

Congressional Member Organizations (CMOs) are “study groups, conferences, coalitions, or caucuses, that include only members of Congress and focus on legislative and political issues of common interest or concern.” Among the CMOs are the Congressional Black Caucus, Congressional Caucus for Women’s Issues, Minor League Baseball Caucus, Friends of Norway Caucus, and the Internet Caucus.

These groups publish newsletters, legislative updates, roll call vote analyses, research reports and “Dear Colleague” letters–largely documents that track legislative developments.


Good Question: What Is A Congressional Caucus?


A Congressional Staff Organization (CSO) is an organization, a majority of whose members are House employees, that exists for the purpose of facilitating interaction among congressional staff. Each Congress, CSOs must register with the Committee on House Administration. At least one officer of a CSO must be an employee of the House, and all officers must be employees of the House or Senate.

Among the CSOs are the Capitol Hill Bible Study Staff Association, Catholic Staff Association, Congressional Hockey Caucus Staff Association, Hispanic Conservatives Congressional Staff Association, House Chiefs of Staff Association, and Women’s Congressional Staff Association.

Another type of CSO is the Congressional Spouse Organization, such as The Congressional Club:

An active member is the spouse of a sitting or former Member of Congress, Supreme Court Justice, or Member of the President’s Cabinet; and once a member, always a member, upon payment of annual dues. Associate membership is only open to active members’ adult children or spouses of adult children.

Also see Blue Dog Coalition / CMO; “Dear Colleague” letters; § 4.201 Congressional Spouse Organizations, § 5.121, Selected Caucuses and Informal Groups, and § 6.22, Sample “Dear Colleague” Letter, in Congressional Deskbook.







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