Committee sizes and ratios are determined before Senators are assigned to committees. Although the size of each committee is set in Senate rules, changes to these rules often result from interparty negotiations before each Congress. Senate party leaders also negotiate the party ratio of each committee during the discussions of committee size. Senate rules call for the election of Senators to standing committees by the entire membership of the chamber. Senate Rule XXIV, paragraph 1 states: "In the appointment of the standing committees, or to fill vacancies thereon, the Senate, unless otherwise ordered, shall by resolution appoint the chairman of each such committee and the other members thereof." These elections are based on nominations made by the parties, but Senators do not officially take seats on committees until they are elected by the entire Senate. While Senate rules are fairly clear regarding how nominations are to be approved , they do not address how the nominations of Senators to committees are to be made . In practice, each party vests its conference with the authority to make nominations to standing committees. Senate Republicans primarily use a Committee on Committees for this purpose, although the Republican leader nominates Senators for assignment to some standing committees. Senate Democrats use a Steering and Outreach Committee to nominate Democrats for assignment to all standing committees. The processes these two panels use are distinct, but the nominations of each panel require the approval of the full party conference and, ultimately, the Senate. Senate approval of the committee nominations of its parties usually is pro forma because the Senate respects the work of each party. It has been customary for third-party and independent Senators to caucus with one of the major parties. At least for committee assignment purposes, such a Senator is considered a member of that conference and receives his or her committee assignments from that conference through its regular processes. As used in this report, the term "standing committees" refers to the permanent panels identified in Senate rules. The rules also list the jurisdiction of each committee. Within their jurisdictions, the standing committees consider bills and issues, recommend measures for consideration by the Senate, and conduct oversight of agencies, programs, and activities. Most standing committees recommend authorized levels of funds for government operations and for new and existing programs within their jurisdiction. The term "non-standing committee" is used here to describe joint committees, and select, special, and other Senate committees. Congress currently has four joint committees that are permanent and that conduct studies or perform housekeeping tasks rather than consider legislation. Members of both chambers serve on them. The assignment of Senators to conference committees (temporary joint committees formed to resolve differences in House- and Senate-passed versions of a measure) is not addressed by this report. On occasion, the Senate has created select, special, and other committees. Sometimes such panels are created for a short time to complete a specific task, as in the case of the Special Committee to Investigate Whitewater Development Corporation and Related Matters. The committee was created on May 17, 1995, and expired on June 17, 1996. Select, special, and other committees have sometimes existed for many years. Some, like the Special Committee on Aging, conduct studies and investigations. Others, such as the Select Committee on Intelligence, have legislative jurisdiction, meaning they consider measures and recommend them for action by the Senate. This report focuses primarily on how Senators are elected to standing committees. It first relates how standing committee sizes and ratios are set. It then identifies the classification of committees the Senate uses for assignment purposes, and the chamber limitations on committee service. It next describes the procedures that each party uses to recommend Senators for assignment to standing committees, and how the full chamber approves these recommendations. Finally, it summarizes the processes used to appoint Senators to non-standing committees. The report does not address how committee chairs and ranking minority members are selected, or how subcommittee members and leaders are chosen. Following general elections, one of the first orders of business for leaders of both parties in the Senate is the setting of standing committee ratios and sizes. Committee ratios and sizes usually are set simultaneously because of their interrelationship. These determinations usually are made before assigning Senators to standing committees because the party organizations that make committee assignments need to know the numbers of seats available to each party on each committee. The determination of ratios and sizes sometimes is made with an awareness of Senators' specific desires for seats on particular panels. The ratio of Republicans to Democrats on each standing committee usually is determined at early organization meetings held in the interval between the general election and the beginning of a Congress. Since the rules of the chamber do not contain provisions regarding committee ratios generally, the majority party possesses the potential to set them unilaterally. In practice, however, ratios generally are set after negotiation between leaders of the two parties. Committee ratios usually parallel the overall party ratio in the Senate, with each party occupying a percentage of seats on all committees consistent with the percentage of seats it has in the Senate. Senate Rule XXV sets out the number of Senators allowed on each committee. However, these committee sizes typically are amended at the beginning of a Congress through Senate approval of one or more resolutions. Under Senate rules, the majority and minority leaders may agree to adjust temporarily the size of one or more standing committees, by up to two members, to accord the majority party a majority of the membership of every standing committee (a "working majority"). In many cases, however, amendments to committee sizes are made to accommodate the interests and needs of Senators in serving on committees. These amendments, and therefore committee sizes, are usually the product of consultation between the party leaders. The sizes of standing committees normally differ. In the 109 th Congress, the Senate standing committees ranged from 13 to 28 members. Committees with broader jurisdictions generally are larger than those whose jurisdiction is more narrowly defined. Committees considered more prestigious or otherwise sought-after also tend to be larger. The Senate Select Committee on Ethics has an equal party ratio pursuant to the resolution which created the panel. The rules of the Senate divide its standing and other committees into categories for purposes of assigning all Senators to committees. In particular, Rule XXV, paragraphs 2 and 3 establish the categories of committees, popularly called the "A," "B," and "C" committees. The "A" and "B" categories, are as follows: " A " COMMITTEES Agriculture, Nutrition, and Forestry Appropriations Armed Services Banking, Housing, and Urban Affairs Commerce, Science, and Transportation Energy and Natural Resources Environment and Public Works Finance Foreign Relations Health, Education, Labor, and Pensions Homeland Security and Governmental Affairs Judiciary Select Committee on Intelligence " B " COMMITTEES Budget Rules and Administration Small Business and Entrepreneurship Veterans' Affairs Special Committee on Aging Joint Economic Committee The "C" category comprises three non-standing committees: the Select Committee on Ethics, the Committee on Indian Affairs, and the Joint Committee on Taxation. The Joint Committee on the Library and the Joint Committee on Printing are not listed in any category, but are treated as "C" committees for assignment purposes. Rule XXV, paragraph 4 places restrictions on Senators' committee membership based on these categories. The restrictions are intended to treat Senators equitably in the assignment process. Essentially, each Senator is limited to service on two of the "A" committees, and one of the "B" committees. Service on "C" committees is unrestricted. Exceptions to the restrictions are recommended by the pertinent party conference and then officially authorized through Senate approval of a resolution affecting one or more Senators. Sometimes these exceptions are authorized to accord the majority party a working majority on a committee, whereas at other times exceptions are made to accommodate the preferences and needs of individual Senators. The committee assignment process used by Senate Republicans involves three steps. First, the Committee on Committees and the Republican leader nominate Republican Senators for committee assignments. Second, these recommendations are submitted for approval to the Republican Conference, the organization of all Republican Senators. Third, the recommendations are incorporated into one or more Senate resolutions and approved by the full Senate. The chair and other members of the Committee on Committees are appointed by the chair of the Republican Conference, subject to confirmation by the Republican Conference. The size of the Committee on Committees fluctuates from Congress to Congress. In recent Congresses, it consisted of nine members, including the majority leader, who served on the committee ex-officio and did not chair the panel. The Committee on Committees is relatively small, in part because it relies on a seniority formula in assigning both returning and newly elected Republican Senators. The formula makes the assignment process somewhat automatic; the absence of significant debate and voting thus requires comparatively few members. Under Republican Conference rules, the Committee on Committees nominates Republicans for assignment to all category "A" committees, as well as to the Committee on Rules and Administration. According to Conference Rule V, nominations for assignment to other committees are made by the Republican leader (unless otherwise specified by law). In practice, the Republican leader also has nominated members to serve on the Committee on Rules and Administration. Following a general election, all Republican Senators are asked to submit their committee assignment preferences to the Committee on Committees. The committee prefers that these requests be listed in order of priority. It is considered useful for new Republican Senators to consult with party leaders and the chairs (or ranking members) of desired committees to assess the likelihood of receiving a desired assignment. Under the seniority system used by Senate Republicans, for example, a freshman is likely to have more success if his or her first choice is not a committee seat desired by an incumbent or a "more senior" freshman. Informing party and committee leaders of one's committee preferences also acts to alert them to one's substantive policy interests. In December or January following the general election, the Committee on Committees first meets to nominate Senators to committees. Senate Rule XXV, as described above, sets out the rules and restrictions that guide the committee in distributing standing committee seats. The Republican Conference has established additional rules and guidelines that govern the procedures of the Committee on Committees. One such rule generally prohibits any Republican from serving on more than one of the "Super A," or "big four" category "A," committees: Appropriations, Armed Services, Finance, and Foreign Relations. Conference rules also generally prohibit two Republican Senators from the same state from serving on the same panel. Republicans usually nominate Senators to "A" committees before filling vacancies on other committees. The seniority formula used by the Committee on Committees in making assignment nominations is as follows. First, in order of seniority in the chamber, each incumbent chooses two committee assignments; incumbents may decide to retain current committee seats or choose among existing vacancies. However, a Senator who has served on a committee and lost a seat due to a change in the party ratio has priority over any and all Senators to claim the first vacancy on the committee. While such instances have been rare, they have occurred when party control of the Senate has changed. Second, each newly elected Senator chooses seats in order of seniority, based on previous service in the Senate; previous service in the U.S. House of Representatives and length of service in the House; and previous service as a state governor. Ties in seniority of freshmen are broken by draw. In addition, every newly elected Senator receives one assignment before any newly elected Senator receives a second assignment. The Republican Leader has the authority to appoint half of all vacancies on each "A" committee. If there is an odd number of vacancies, the Leader can appoint half plus one of all vacancies. Effective in the 108 th Congress, all Republican Members are offered two "A" committee slots in order of seniority. Each Member can retain only one "B" committee assignment from the previous Congress. Following this process, the Republican Leader makes any remaining "A" committee assignments. Conference rules provide a guideline governing the time frame for Senators to choose among assignment options presented by the Committee on Committees. If a Senator is presented with selection options before noon on a given day, the Senator should notify the Committee on Committees of his or her decision by the close of business on that day. If a Senator is presented with selection options after noon on a particular day, then a decision should be made by noon on the next business day. This provision is designed to expedite the assignment process by preventing Senators from engaging in lengthy deliberation that could delay the assignment of Senators with less seniority. Rank on each committee generally is determined by length of continuous service on the committee. If a Senator leaves a committee and returns in a subsequent Congress, the Senator likely would lose his or her previous seniority. However, the chair (or ranking member) of a committee need not be the Member with the longest committee service. While nominations for assignment to "non-A" committees (except, officially, Rules and Administration) are at the discretion of the Republican leader, the leader generally follows the seniority formula used by the Committee on Committees. Moreover, the leader usually works in close cooperation with the chair and other members of the Committee on Committees. Through this system, the assignment process is relatively consensus-oriented and automatic, and formal votes on nominees usually are not necessary. In assigning freshmen, the Committee on Committees does not consider the multiple factors relied upon by the Senate Democrats' party organization (discussed below); instead, the most important factor appears to be Senators' requests. Personal efforts to compete for committee seats appear to be minimal (though not unknown) as compared with Senate Democrats. When the Committee on Committees and the Republican leader have finished their work, they submit their recommendations for assignment to the Republican Conference. For each committee, a slate of committee members in order of proposed seniority is presented for consideration. Voting by recorded written ballot, as specified by conference rules, ordinarily is not necessary. The conference usually adopts the recommendations by unanimous consent, presumably because they are based largely on seniority. Once accepted by the Republican Conference, the assignment recommendations are packaged into one or more Senate resolutions that are submitted to the full Senate for approval, usually by the Republican leader. Because the resolutions are privileged, they can be brought up at any time. These resolutions are amendable and any Senator may demand a separate vote on the appointment of the chair or on the other members of a standing committee. However, the resolutions usually are adopted without incident. Nominations rarely are challenged on the floor because it is in the parties where decisions are made; by custom, neither party has challenged the nominations of the other party. Indeed, the routine character of the Senate's approval of nominations highlights the importance of the nomination process. In filling vacancies that occur on standing committees after their initial organization, Senate Republicans follow the same procedure used for each new Congress. Committee vacancies may occur during the course of a Congress because party leaders decide to change a committee's size or party ratio, or because Members die, change parties, or resign from the Senate. A new Senator replacing a late or former Senator may be chosen to fill the vacated committee seats. However, if the new Senator is of the opposite party from the departed Senator, adjustments in sizes and ratios often are needed to make slots for the new Senator. Moreover, incumbents also might seek to compete for the newly open committee seats, especially if they occur on one of the more prestigious panels, such as the Appropriations Committee or the Finance Committee. When an incumbent is chosen to fill a committee vacancy, that Senator often gives up an existing assignment to comply with party or chamber assignment limitations (although a waiver might be granted). This may cause a chain reaction involving a series of shifts of committee assignments. There are three steps in the nomination and assignment process for Senate Democrats. The first is for the Democratic Steering and Outreach Committee to make nominations for committee assignments. The second consists of approval of the nominations by the Democratic Conference, which comprises all Democrats in the Senate. The final step is for the assignment rosters to be incorporated into one or more Senate resolutions and considered and approved by the full Senate. Senate Democrats do not have written rules governing this assignment process, as do Senate Republicans. The size of the Steering and Outreach Committee is set by the Democratic Conference. The Democratic leader serves on the committee and appoints its members, subject to ratification by the conference. Steering and Outreach Committee members (except party leaders) may not serve simultaneously on the Democratic Policy Committee. Instead of chairing the panel, in the past few Congresses the Democratic leader has named another Senator as chair. In appointing Senators to vacancies, the Democratic leader attempts to achieve regional balance on the committee under a system that divides the country into four regions. The Steering and Outreach Committee continues from Congress to Congress, appointing Democratic Senators to vacancies as they arise. In the 109 th Congress, the Steering and Outreach Committee had 18 members, including the Democratic leader, the Democratic whip, the chief deputy Democratic whip, and a deputy Democratic whip. While it is not composed exclusively of the most senior Democrats, the Steering and Outreach Committee includes many committee ranking members. Once elected to the Senate, it is customary for new Democratic Senators to communicate committee preferences to the Steering and Outreach Committee. While the Democratic leader and the Steering and Outreach Committee chair generally solicit committee preferences from new Senators, incumbents desiring to switch committees usually initiate contact. Democrats are encouraged to submit their requests for assignment as early as possible. A Senator who delays risks the potential of not securing primary or even secondary requests. While the Steering and Outreach Committee does not require Senators to rank order their assignment preferences, many have done so in the past to give the committee alternatives if it is unable to grant initial requests. It appears to be important for Senators-elect, in formulating their preferences, to consult with party leaders, Steering and Outreach Committee members, and the chairs (or ranking members) of preferred committees. This consultation acts both to notify senior Senators of a freshman's substantive interests and to inform the freshman Senator of the likelihood that he or she will be assigned to preferred committees. The Steering and Outreach Committee organizes, and begins the process of making committee assignments, in November or December following the general election. Unlike its Senate Republican counterpart, the committee nominates Senators for assignment to every standing committee. Given that most returning Senators choose to retain their assignments from the previous Congress, most of the committee's work involves matching freshman Democrats with vacancies created by retirement or electoral defeat, as well as by adjustments in committee sizes and ratios. In making nominations for committee assignments, the Steering and Outreach Committee is bound by the categories of committees and the limitations on committee assignments contained in Senate Rule XXV, discussed earlier. Within the confines of these restrictions, the Democratic Conference has formulated additional restrictions for its own members. One such restriction generally limits each Senator to service on no more than one of the "Super A," or "big four" "A," committees: Appropriations, Armed Services, Finance, and Foreign Relations. Senate Democrats also have an informal practice of prohibiting two Democratic Senators from the same state from serving on the same committee. In addition to these chamber and party restrictions, the Steering and Outreach Committee considers many factors. These include Senators' preferences, state demographics, length of time since the state was last represented on the committee, perceived willingness to support the party, policy views, and personal and occupational backgrounds. Personal intervention, by the requesting Senator or another Senator, is sometimes helpful. The Steering and Outreach Committee usually fills vacancies on "A" committees before slots on other panels. Because the Steering and Outreach Committee does not rely on a seniority formula in assigning Senators, its process is relatively less automatic than that of Senate Republicans. For Democrats, there are no rules guaranteeing priority in assignment to incumbents switching committees, or governing the seniority of freshmen in choosing assignments. However, a Senator who served on a committee but lost the seat due to a change in the party ratio generally receives priority in assignment to a vacancy on that committee. Nominations for assignment are made on a seat-by-seat basis, and Steering and Outreach members usually make nominations by consensus. However, if significant competition exists for a particular seat, then secret balloting usually is conducted and the majority-vote winner is granted the nomination. Senators who do not win election to their most preferred committee seat are protected by the "Johnson Rule," providing that all Democrats are appointed to one "A" committee before any Senator receives a second assignment. Rank on each committee generally is determined by length of continuous service on the committee. If a Senator leaves a committee and returns to it in a subsequent Congress, the Senator likely would lose his or her previous seniority. However, the ranking member (or chair) need not be the Member with the longest committee service. The committee rankings of Senators assigned to a committee at the same time generally are determined by their seniority in their party in the Senate. When an incumbent and a freshman are assigned to a committee at the same time, the incumbent ordinarily ranks higher than the freshman. Similarly, when elected, each freshman is given a seniority ranking among Senate Democrats, and his or her rank on committees is based on this overall chamber ranking. Once all veteran and freshman Democratic Senators have been recommended for assignment, the roster is forwarded to the Senate Democratic Conference. While separate votes are possible, the conference usually ratifies the entire slate of assignments by unanimous consent. After ratification, the assignment recommendations are packaged into one or more Senate resolutions and submitted on the Senate floor for adoption. The resolutions usually are submitted by the Democratic leader, and they can be brought up at any time because they are privileged. The resolutions also are amendable, and any Senator may demand a separate vote on the appointment of any member. However, the resolutions containing the committee rosters usually pass without debate, by voice vote. It is in the party where significant debate and decision-making already has occurred regarding committee assignments. In filling vacancies that occur on standing committees after their initial organization, Senate Democrats follow the same procedure used for each new Congress. Committee vacancies may occur during the course of a Congress because party leaders decide to change a committee's size or party ratio, or because Members die, change parties, or resign from the Senate. A new Senator replacing a late or former Senator may be chosen to fill the vacated committee seats. However, if the new Senator is of the opposite party from the departed Senator, adjustments in sizes and ratios often are needed to make slots for the new Senator. Moreover, incumbents also might seek to compete for the newly open committee seats, especially if they occur on one of the more prestigious panels, such as the Appropriations Committee or the Finance Committee. When an incumbent is chosen to fill a committee vacancy, that Senator often gives up an existing assignment to comply with party or chamber assignment limitations (although a waiver might be granted.) This may cause a chain reaction involving a series of shifts of committee assignments. Non-standing committees are divided between the so-called category "B" committees and category "C" committees. The Special Committee on Aging and the Joint Economic Committee, along with four standing committees, are included in the "B" category of committees. Under Senate rules, no Senator may serve on more than one "B" committee, whether standing or non-standing. The Select Committee on Ethics, the Committee on Indian Affairs, and the Joint Committees on Taxation, the Library, and Printing essentially are treated as "C" committees, although Joint Library and Joint Printing are not explicitly listed as such in Senate rules. The "C" committees are exempt from the assignment limitations in Senate rules, so a Senator may serve on any number of them without regard to his or her other assignments. Specific rules regarding Senate membership on and appointments to non-standing committees often are contained in the legislation creating these panels. Thus, the procedures vary from committee to committee. A review of the legislation establishing the non-standing committees, and the appointment practices that have evolved, reveal that party leaders are usually included in the process. The members of the Select Committee on Ethics and the Special Committee on Aging are elected by the Senate by resolution, essentially in the same manner as the standing committees. The Ethics Committee is the only Senate committee with an equal party ratio, consisting of three Senators from each party. Republican members of both committees are chosen by the Republican leader and confirmed by the Republican Conference before election by the full Senate. Democratic members of the Ethics Committee are selected initially by the Democratic leader. In contrast, Democrats on the Aging Committee are nominated by the Steering and Outreach Committee and confirmed by the Democratic Conference before election by the full Senate. Majority-party Senators are appointed to the Select Committee on Intelligence on the recommendation of the majority leader, and minority-party Senators on the recommendation of the minority leader. Senators are appointed to this committee from the Appropriations, Armed Services, Foreign Relations, and Judiciary Committees, as well as from the Senate "at large." The majority and minority leaders, as well as the chair and ranking member of the Armed Services Committee serve on the committee as ex-officio , non-voting members. The resolution creating the Intelligence Committee provided for a rotation of membership; no Senator could serve on the committee for more than eight years of continuous service. To the extent practicable, one-third of the Senators appointed to the committee at the outset of each Congress should be Senators who did not serve on it in the preceding Congress. S.Res. 445 , adopted October 9, 2004, ended the eight-year limitation on the Intelligence Committee. The majority and minority leaders recommend Senators for appointment to the Committee on Indian Affairs, but the members are officially appointed by the President of the Senate (the Vice President of the United States). Appointments to the Committee on Indian Affairs are announced to the Senate from the chair. Ten Senators, six from the majority party and four from the minority party, are appointed to the Joint Economic Committee by the President of the Senate. The Senate membership of the Joint Committee on Taxation consists of five Senators from the Committee on Finance, three from the majority and two from the minority, chosen by the Finance Committee. Appointments to both joint committees are announced to the Senate from the chair. The Senate participants on the Joint Committee on the Library and the Joint Committee on Printing are selected by the Committee on Rules and Administration from among the committee's members. The chair and four other members of the Rules Committee are to serve on each joint committee. However, in some Congresses, the House and Senate have agreed to a concurrent resolution allowing another member of the Senate Rules Committee to serve on the Joint Committee on the Library in place of the Rules Committee's chair. The membership of the Joint Committee on Printing typically includes not only the chair but also the ranking minority member of the Senate Rules Committee. Members of both joint committees are elected by the Senate by resolution.

Summary:
Because of the importance of committee work, Senators consider desirable committee assignments a priority. The key to securing favorable committee slots is often said to be targeting committee seats that match the legislator's skills, expertise, and policy concerns. After general elections are over, one of the first orders of business for Senate leaders is setting the sizes and ratios of committees. Although the size of each standing committee is set in Senate rules, changes in these sizes often result from inter-party negotiations before each new Congress. Senate party leaders also negotiate the party ratios on standing committees. Determinations of sizes and ratios usually are made before the process of assigning Senators to committees. Once sizes and ratios of standing committees are determined, a panel for each party nominates colleagues for committee assignments. Senate Republicans primarily use a Committee on Committees for this purpose, although the Republican leader nominates Senators for assignment to some standing committees. Senate Democrats use a Steering and Outreach Committee to nominate Democrats for assignment to all standing committees. The processes these panels use are distinct. Republicans rely on a seniority formula to make nominations, while Democrats make nominations on a seat-by-seat basis, considering a variety of factors. The processes also have many common features. After the general election, each panel solicits preferences for committee assignment from party colleagues, then matches these preferences with vacancies on standing committees. Senate rules, along with party rules and practices, guide the work of the Committee on Committees and the Steering and Outreach Committee. Senate rules, for instance, divide the standing and other Senate committees into three groups, the so-called "A" "B" and "C" categories. Senators must serve on two "A" committees and may serve on one "B" committee, and any number of "C" committees. Exceptions to these restrictions are sometimes approved by the Senate. Both parties place further limitations, for example, by generally prohibiting two Senators from the same party and state from serving on the same committee. The nominations of each of these panels require the approval of the pertinent full party conference and ultimately the Senate. Approval at both stages usually is granted easily, because of the debate and decision-making earlier in the process. Specific rules regarding Senate membership on and appointments to non-standing committees vary from committee to committee, but party leaders usually are included in the process. For more information on Senate and party rules governing assignment limitations, see CRS Report 98-183, Senate Committees: Categories and Rules for Committee Assignments.