Sponsorship and Cosponsorship of Senate Bills

Sponsorship and Cosponsorship of Senate Bills

Sponsorship and Cosponsorship of Senate Bills

Updated August 11, 2025 (98-279)
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Summary

A Senator who introduces a bill or resolution in the Senate is called its sponsor. Several Senators together may introduce a measure, but only the Senator whose name appears first on the bill is considered its sponsor; the others are cosponsors. A bill can have only one sponsor, but there is no limit on the number of cosponsors it may have.

When a Senator has determined that a bill is ready for introduction, it can be delivered to the bill clerk's desk on the chamber floor when the Senate is in session. The sponsor must sign the bill and may attach the names of any cosponsors on a separate form. Senators whose names are submitted with a bill at the time of introduction are commonly referred to as "original" cosponsors. After a bill has been introduced, a Senator may request to be added as a cosponsor by unanimous consent. Sponsors may also request unanimous consent to add colleagues as cosponsors to their bills.

Supporters of a bill often seek cosponsors to demonstrate its level of support among Senators. One of the most common techniques to attract cosponsors is the "Dear Colleague" letter, a notice delivered to some or all Senate offices either in print or by email soliciting support for the bill. These letters typically explain the issue or problem the legislation seeks to address, the key policy elements it contains, and the likely impact it would have if made into law.

A Senator may introduce a bill as a courtesy, such as legislation proposed by the President, in which case the bill would be designated in the Congressional Record as having been introduced "by request." A Senator may also introduce legislation on behalf of another Senator without having to assume sponsorship. Once a bill has been handed to the clerk, it becomes the property of the Senate and cannot be withdrawn. If a Senator desires that no action be taken on the bill, the Senator may request unanimous consent that action on the bill be indefinitely postponed.

Decisions to cosponsor legislation can be made for a variety of reasons, some of which might be unrelated to the text of the bill itself. As such, cosponsorship should not be equated with a vote for final passage.

A Senator who introduces a bill or resolution in the Senate is called its sponsor. Several Senators together may introduce a measure, but only the Senator whose name appears first on the bill is considered its sponsor; the others are cosponsors. A bill can have only one sponsor, but there is no limit on the number of cosponsors it may have.¹

Sponsorship of a Bill

At the beginning of each new Congress, the Senate traditionally adopts a standing order allowing Senators to introduce bills and resolutions at any time the chamber is in session by presenting them to the bill clerk seated at the desk on the Senate floor.² Most measures are introduced in this fashion. Senators may also introduce measures from the floor as part of "morning business" under Senate Rule VII. In practice, however, morning business seldom occurs as provided in Rule VII. Instead, on most days, the Senate arranges by unanimous consent for a period of morning business to occur at some later point. Senators may introduce measures from the floor during this period.³

Senators typically sponsor bills they support. A Senator may introduce a bill as a courtesy, such as legislation proposed by the President, in which case the bill would be designated in the Congressional Record as having been introduced "by request." A Senator may also introduce legislation on behalf of another Senator without having to assume sponsorship themselves.⁴ Once a bill has been handed to the clerk, it becomes the property of the Senate and cannot be withdrawn. A bill sponsored by a Senator who has since departed the chamber can still be acted upon by the Senate. The text of a departed Senator's bill also may be introduced as a new bill with a sitting Senator identified as its sponsor.

Some bills become popularly associated with the names of two or more Senators; for instance, the Gramm-Rudman-Hollings Deficit Control Act of 1985, the Nunn-Lugar Cooperative Threat Reduction Act of 1991, or the McCain-Feingold Campaign Reform Act of 2002. Although these popular associations may suggest otherwise, Senate rules do not allow a bill to have multiple sponsors. Even still, the strategy of associating legislation with the names of two or more Senators can be useful in gaining support across partisan or ideological ranks. As Senator Ted Kennedy (D-MA) explained: "When Strom [Thurmond] and I introduce a bill together, it is either an idea whose time has come, or one of us has not read the bill."⁵ A "Kennedy-Thurmond" bill would have conveyed a clear signal that the measure enjoyed support from across the ideological spectrum.

Most measures are introduced by individual Senators, but Senate committees may also report an "original" bill for chamber consideration. As Senate Rule XXV states, standing committees have "leave to report by bill or otherwise on matters within their respective jurisdictions." Although the relevant committee chair may be identified as the sponsor in these instances, the measure is perhaps best understood as a product that incorporates views and input from other committee members as well.⁶ Original bills may not have cosponsors.

Cosponsorship of a Bill

When Senators introduce a bill, they commonly attach a form listing the names of cosponsors.⁷ Cosponsorship is generally understood to signify a Senator's support for the proposal. Prior to introduction, Senators may cosponsor a measure by contacting the office of the sponsor and requesting that their names be included on the bill or resolution. Initial (or "original") cosponsors can be added until the measure is presented to the bill clerk on the floor of the Senate chamber. Thereafter, unanimous consent is required to include additional cosponsors on the measure.⁸ A Senator may offer this request when recognized on the Senate floor, or, alternatively, deliver to the cloakroom a cosponsorship form that bears an original signature of the Senator requesting to be added as a cosponsor.

The names of additional cosponsors will appear on the printed version of the bill only if there is a subsequent printing of it. Under regulations set forth by the Joint Committee on Printing, a bill cannot be reprinted solely for the purpose of adding cosponsors (even by unanimous consent).⁹ A current list of cosponsors may be identified through a search of Congress.gov, or the Congressional Record.¹⁰

Sponsors of a bill often seek cosponsors to demonstrate its level of support among Senators. One of the most common techniques to attract cosponsors is the "Dear Colleague" letter, a notice delivered to some or all Senate offices either in print or by email soliciting support for the bill. These letters typically explain the issue or problem the legislation seeks to address, the key policy elements it contains, and the likely impact it would have if enacted into law. Contact information of a staff aide is usually included for the benefit of Senate offices interested in cosponsoring the measure. No Senate rules or any formal procedures govern "Dear Colleague" letters. They are, in effect, advertisements for the sponsoring Senator's legislation.¹¹

On the day a measure is introduced, the sponsor may direct the clerk to hold the bill at the desk for the purpose of collecting cosponsors prior to its referral to committee. To hold a bill at the desk beyond the date of its introduction requires the unanimous consent of the Senate.¹²

The connection between cosponsorship and legislative outcomes has been the subject of considerable scholarly research. Much of the empirical work in this area suggests that cosponsorship has a positive but limited impact on a bill's prospects for final passage. As one prominent study concluded

[C]osponsorship matters for legislative success, but only barely. Significant effects due to cosponsorship crop up at different stages of the legislative process. When bills are referenced to a committee, bills with cosponsors are more likely than bills with no cosponsors to receive some consideration. Likewise, cosponsored bills are more likely to make it out of committee, however, the impact of cosponsorship is slight. It has even less impact on the final passage of bills.¹³

Decisions to cosponsor legislation can be made for a variety of reasons, some of which might be unrelated to the text of the bill itself. As such, cosponsorship should not be equated with a vote for final passage. In some cases the text of a measure might have been amended following its introduction in ways a cosponsor can no longer support. In addition, Senate norms of behavior have long emphasized collegiality and deference to one's colleagues, and some Senators may view cosponsorship as the legislative equivalent of a common courtesy. Senator Everett Dirksen (R-IL) expressed the sentiment this way:

The bill may be 50 pages long, and I will not know what is in it from the enacting clause to the last period. But I do not wish to affront a Senator, and if he gives me a sufficient sales talk, I am likely to say, "All right, go ahead and add my name." Then, when we finally get around to it, I discover at long last what I actually put my name to. Perhaps I will not like it. But how do you get out from under it? Because my name is there, notwithstanding. I could at some point take it off, but one does not wish to affront a fellow Senator by doing that.¹⁴

This report was originally prepared by former CRS Specialist Richard C. Sachs. Congressional clients may direct any inquiries to the current author.

Footnotes

1.

Congressional Record, vol. 50, part 6, (October 27, 1913), p. 5798.

2.

Congressional Record, daily edition, vol. 171 (January 3, 2025), p. S9.

3.

When the Senate adjourns for longer periods, such as during the traditional August recess, it will often arrive at a unanimous consent agreement providing that "no business shall be conducted" on the specified days the Senate is scheduled to meet in "pro-forma" session. See Congressional Record, daily edition, vol. 171 (August 2, 2025), p. S5506. Language to suspend the Senate's "business" includes the introduction of measures and the addition of cosponsors, which would need to wait until the Senate returns from recess to become official. For information on bill introduction, see CRS Report R44195, Introducing a Senate Bill or Resolution, by Mark J. Oleszek.

4.

In these cases, the bill will appear in the Congressional Record as having been introduced by one Senator for another Senator. For instance, on January 4, 2017, Minority Leader Charles Schumer introduced S. 30 on behalf of Senator Feinstein, who sponsored the bill. See Congressional Record, daily edition, vol. 163 (January 4, 2017), p. S59.

5.

Quoted in Walter Oleszek, Roger Davidson, Eric Schickler, and Frances Lee, Congress and Its Members, 16th ed. (Washington, DC: CQ Press, 2017), p. 221.

6.

Technically speaking, an original bill is not considered to have a sponsor under Senate rules. When an original bill is reported and a final draft is printed, a Senator (usually the chair) will deliver the final draft to the bill clerk's desk on the chamber floor where it will be assigned a bill number and placed on the calendar. The name of the Senator who brought the legislation forward will be indicated on the bill, but this indication is not tantamount to sponsorship.

7.

Cosponsorship forms are available for download on Webster, the Senate's internal website, http://webster.senate.gov. Only Senate offices have access to Webster. This form may be used to either add or subtract cosponsors of bills, resolutions, and amendments.

8.

After a bill has been introduced it requires unanimous consent to remove a Senator as a cosponsor, and either the sponsor or a cosponsor may make this request. Proceedings to this effect can be found in the Congressional Record, vol. 153, part 1 (May 2, 2007), p. S5493.

9.

Congressional Record, vol. 97, part 2 (March 21, 1951), p. 2723.

10.

Available at http://congress.gov. Cosponsors who are added to a bill after its introduction will appear in the Congressional Record under the heading "Additional Cosponsors."

11.

For further information, see CRS Report R44768, "Dear Colleague" Letters in the House of Representatives: Past Practices and Issues for Congress, by Jacob R. Straus.

12.

During the 90th Congress (1967-1968) the Senate debated at some length the practice of holding a bill at the desk to gain cosponsors. See Congressional Record, vol. 113, part 3 (February 16, 1967), pp. 3725-3734.

13.

Rick Wilson and Cheryl Young, "Cosponsorship in the U.S. Congress," Legislative Studies Quarterly, vol. 22, no. 1 (February 1997), p. 40.

14.

Congressional Record, vol. 113, part 3 (February 16, 1967), p. 3725.