List of United States senators who switched parties

This list includes United States senators who switched parties while serving in the Senate.

Senator	State	Date	Congress	Old party	New party	Notes
James H. Kyle	South Dakota	1891	52nd	Independent	Populist
William Morris Stewart	Nevada	1893	53rd	Republican	Silver Republican	The Silver Republicans' seniority and committee assignments were not affected by their having left the party.^[1]
John P. Jones	Nevada	September 4, 1894	53rd	Republican	Silver Republican
Henry M. Teller	Colorado	June 17, 1896	54th	Republican	Silver Republican
Lee Mantle	Montana			Republican	Silver Republican
Richard F. Pettigrew	South Dakota			Republican	Silver Republican
Frank J. Cannon	Utah			Republican	Silver Republican
Fred Dubois	Idaho	1896		Republican	Silver Republican
James H. Kyle	South Dakota	1897	55th	Populist	Republican
William Morris Stewart	Nevada	December 4, 1899	56th	Silver Republican	Republican

Senator	State	Date	Congress	Old party	New party	Notes
John P. Jones	Nevada	1901	56th	Silver Republican	Republican
Fred Dubois	Idaho	1901		Silver Republican	Democratic	DuBois lost his re-election bid in 1896, was again elected as a Silver Republican in 1900, but became a Democrat early in the term.
Henry M. Teller	Colorado	March 4, 1901		Silver Republican	Democratic
Miles Poindexter	Washington	1913	63rd	Republican	Progressive
Miles Poindexter	Washington	1915	64th	Progressive	Republican
Robert M. La Follette Jr.	Wisconsin	1935	74th	Republican	Progressive	Caucused with the Republicans; briefly returned before losing in 1946.
George W. Norris	Nebraska	1937	75th	Republican	Independent
Henrik Shipstead	Minnesota	1940	76th	Farmer–Labor	Republican
Wayne Morse	Oregon	1953	83rd	Republican	Independent
Wayne Morse	Oregon	February 17, 1955	84th	Independent	Democratic
Strom Thurmond	South Carolina	September 16, 1964	88th	Democratic	Republican
Harry F. Byrd Jr.	Virginia	1970	91st	Democratic	Independent	Kept seniority, but did not caucus with the Democrats
James L. Buckley	New York	1976	94th	Conservative	Republican
Richard Shelby	Alabama	November 9, 1994	103rd	Democratic	Republican
Ben Nighthorse Campbell	Colorado	March 3, 1995	104th	Democratic	Republican
Robert Smith	New Hampshire
		July 13, 1999	106th	Republican	Taxpayers
		August 1999		Taxpayers	Independent
		November 1, 1999		Independent	Republican

Senator	State	Date	Congress	Old party	New party	Notes
Jim Jeffords	Vermont	June 6, 2001	107th	Republican	Independent	Caucused with the Democrats. Gave Democrats temporary control of the senate.
Joe Lieberman	Connecticut	2006	110th	Democratic	Independent Democrat	Caucused with the Democrats. Lieberman was re-elected on the Connecticut for Lieberman ticket; however, he never formally joined that political party.
Arlen Specter^[2]	Pennsylvania	April 28, 2009	111th	Republican	Democratic	Originally a Democrat
Kyrsten Sinema^[3]	Arizona	December 9, 2022	117th	Democratic	Independent	Caucused with the Democrats
Joe Manchin^[4]	West Virginia	May 31, 2024	118th	Democratic	Independent	Caucused with the Democrats

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