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A congressional caucus is a group of members of the United States Congress that meets to pursue common legislative objectives. Formally, caucuses are formed as congressional member organizations (CMOs) through the United States House of Representatives and governed under the rules of that chamber. They are not always called caucuses, and are sometimes titled coalitions, study groups, task forces, or working groups. In most other countries, the same kind of group is called an all-party parliamentary group.
Party conferences 
The largest caucuses are the party conferences, which are the partisan caucuses comprising all members of one house from one party (either the Democrats or the Republicans). These are the House Democratic Caucus and House Republican Conference in the House of Representatives and the Senate Democratic Caucus and Senate Republican Conference in the Senate.
The caucuses meet regularly in private closed sessions to set legislative agendas, select committee members and chairs, and hold elections to choose various floor leaders. They also oversee the four Hill committees, political party committees that work to elect members of their own party to Congress.
Ideological conferences 
Other caucuses are organized political factions with a common ideological orientation:
- On the Democratic side, there is the Blue Dog Coalition (conservative Democrats), the New Democrat Coalition (moderate Democrats), and the Congressional Progressive Caucus (liberal and progressive Democrats).
- On the Republican side, there is the Republican Study Committee (conservative Republicans) and the Liberty Caucus, which is sometimes called the Republican Liberty Caucus (libertarian Republicans). The Tea Party Caucus also has 49 Republican members in the House of Representatives and four in the Senate.
Racial and ethnic caucuses 
The Congressional Black Caucus for African-Americans has included members of both chambers, but the election of Barack Obama as President had left no black Senators, making the CBC exclusively Representatives. Senator Roland Burris, who succeeded Barack Obama in the Senate, was a member of the CBC, but Burris left office on November 29, 2010, succeeded by Mark Kirk, so there were again no black Senators. Since Senator Tim Scott of South Carolina was sworn in to replace Senator Jim DeMint, who left the Senate before the end of his term, there is now one black Senator. However, Senator Scott chose not to join the CBC when he was a Representative, and so may elect not to join as a Senator. There are two Hispanics caucuses: The Congressional Hispanic Caucus, for Hispanic Democrats, and the Congressional Hispanic Conference, for Hispanic Republicans. Congressional Republicans formerly belonged to the Hispanic Caucus but later split off to form the Hispanic Conference. The Congressional Asian Pacific American Caucus is for Asian American and Pacific Islander American members, but is not exclusive to such members.
Religious Caucuses 
Judy Chu (D-Monterey Park) and David Valadao (R-Hanford) co-launched the bipartisan American Sikh Congressional Caucus to represent the interests of the American Sikh community. She cited violent crimes against Sikhs in the aftermath of the attacks of September 11, 2001 as being a motivation for the initiation of the caucus.
Interest group caucuses 
The most common caucuses consist of members united as an interest group. These are often bipartisan (comprising both Democrats and Republicans) and bicameral (comprising both Representatives and Senators). For example, the Congressional Bike Caucus works to promote cycling.
The House Committee on House Administration prescribes certain rules for Congressional Member Organizations. Each Congress, CMOs must electronically register with the Committee on House Administration, providing the name of the caucus, a statement of purpose, the CMO officers, and the employee designated to work on issues related to the CMO.
The Committee on House Administration rules include:
- Members of both the House and Senate may participate in 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.
- CMOs have no separate corporate or legal identity. A CMO is not an employing authority. The Members' Representational Allowance (MRA) may not directly support a CMO as an independent entity. A CMO may not be assigned separate office space.
- Neither CMOs nor individual Members may accept goods, funds, or services from private organizations or individuals to support the CMO. Members may use personal funds to support the CMO.
- A Member of a CMO, in support of the objectives of that CMO, may utilize employees (including shared employees) and official resources under the control of the Member to assist the CMO in carrying out its legislative objectives, but no employees may be appointed in the name of a CMO.
- CMOs may not use the frank, nor may a Member lend his or her frank to a CMO.
- A Member may use official resources for communications related to the purpose of a CMO. Any such communications must comply with the Franking Regulations.
- Members may devote a section of their official Web site to CMO issues, but CMOs may not have independent Web pages.
- A Member may use inside mail to communicate information related to a CMO.
- Members may prepare material related to CMO issues for dissemination.
- Official funds may not be used to print or pay for stationery for the CMO.
- Members may refer to their membership in a CMO on their official stationery.
- "Rep. Chu forms caucus to address American Sikh issues". Retrieved 24 april 2013.