List of United States Senators who changed parties

The following are United States Senators who switched parties while serving in the Senate.

Senator	State	Date	Congress	Old party	New party	Notes
William M. Stewart William M. Stewart William Morris Stewart was an American lawyer and politician.-Biography:Stewart was born in Wayne County, New York. As a child he moved with his parents to Trumbull County, Ohio. As a young man he was a mathematics teacher in Ohio. In 1849 he began attending Yale University but left in 1850 to...	Nevada	1893	53rd 53rd United States Congress The Fifty-third United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the United States Senate and the United States House of Representatives. It met in Washington, D.C. from March 4, 1893 to March 4, 1895, during the fifth and sixth...	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Silver Republican Silver Republican Party The Silver Republican Party was a United States political faction active in the 1890s. It was so named because it split from the Republican Party over the issues of "Free Silver" and bimetallism. The main Republican Party supported the gold standard....	The Silver Republicans' seniority and committee assignments were not affected by their having left the party.
John P. Jones John P. Jones John Percival Jones was an American politician who served for 30 years as a Republican United States Senator from Nevada. He made a fortune in silver mining and was a co-founder of the town of Santa Monica, California....	Nevada	September 4, 1894		Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Silver Republican Silver Republican Party The Silver Republican Party was a United States political faction active in the 1890s. It was so named because it split from the Republican Party over the issues of "Free Silver" and bimetallism. The main Republican Party supported the gold standard....
Henry M. Teller Henry Moore Teller Henry Moore Teller was a U.S. politician. Secretary of the Interior between 1882 and 1885.-Biography:He served in the Senate and Cabinet for over thirty years, and was connected with the Free Silver question, beginning in 1880. During that time, he did much in and out of Congress with tongue and...	Colorado	June 17, 1896	54th 54th United States Congress - House of Representatives :-Leadership:- Senate :* President: Adlai E. Stevenson * President pro tempore: William P. Frye - Majority leadership :* Republican Conference Chairman: John Sherman- Minority leadership :...	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Silver Republican Silver Republican Party The Silver Republican Party was a United States political faction active in the 1890s. It was so named because it split from the Republican Party over the issues of "Free Silver" and bimetallism. The main Republican Party supported the gold standard....
Lee Mantle Lee Mantle Lee Mantle was a United States Senator from Montana.Born in Birmingham, England, his mother converted to Mormonism and immigrated to the United States with her children; they settled at Salt Lake City, Utah in 1864...	Montana			Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Silver Republican Silver Republican Party The Silver Republican Party was a United States political faction active in the 1890s. It was so named because it split from the Republican Party over the issues of "Free Silver" and bimetallism. The main Republican Party supported the gold standard....
Richard Pettigrew	South Dakota			Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Silver Republican Silver Republican Party The Silver Republican Party was a United States political faction active in the 1890s. It was so named because it split from the Republican Party over the issues of "Free Silver" and bimetallism. The main Republican Party supported the gold standard....
Frank J. Cannon	Utah			Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Silver Republican Silver Republican Party The Silver Republican Party was a United States political faction active in the 1890s. It was so named because it split from the Republican Party over the issues of "Free Silver" and bimetallism. The main Republican Party supported the gold standard....
Fred Dubois Fred Dubois Fred Thomas Dubois was a controversial American politician who served two terms in the United States Senate from Idaho. He was best-known for his opposition to the gold standard and his efforts to disenfranchise Mormon voters....	Idaho	1896		Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Silver Republican Silver Republican Party The Silver Republican Party was a United States political faction active in the 1890s. It was so named because it split from the Republican Party over the issues of "Free Silver" and bimetallism. The main Republican Party supported the gold standard....
William M. Stewart William M. Stewart William Morris Stewart was an American lawyer and politician.-Biography:Stewart was born in Wayne County, New York. As a child he moved with his parents to Trumbull County, Ohio. As a young man he was a mathematics teacher in Ohio. In 1849 he began attending Yale University but left in 1850 to...	Nevada	December 4, 1899	56th 56th United States Congress -House of Representatives:- Leadership :- Senate :* President: Garret Hobart , until November 21, 1899 , vacant thereafter.* President pro tempore: William P. Frye * Democratic Caucus Chairman: James K. Jones...	Silver Republican Silver Republican Party The Silver Republican Party was a United States political faction active in the 1890s. It was so named because it split from the Republican Party over the issues of "Free Silver" and bimetallism. The main Republican Party supported the gold standard....	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...
John P. Jones John P. Jones John Percival Jones was an American politician who served for 30 years as a Republican United States Senator from Nevada. He made a fortune in silver mining and was a co-founder of the town of Santa Monica, California....	Nevada	1901		Silver Republican Silver Republican Party The Silver Republican Party was a United States political faction active in the 1890s. It was so named because it split from the Republican Party over the issues of "Free Silver" and bimetallism. The main Republican Party supported the gold standard....	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...
Fred Dubois Fred Dubois Fred Thomas Dubois was a controversial American politician who served two terms in the United States Senate from Idaho. He was best-known for his opposition to the gold standard and his efforts to disenfranchise Mormon voters....	Idaho	1901		Silver Republican Silver Republican Party The Silver Republican Party was a United States political faction active in the 1890s. It was so named because it split from the Republican Party over the issues of "Free Silver" and bimetallism. The main Republican Party supported the gold standard....	Democratic Democratic Party (United States) The Democratic Party is one of two major contemporary political parties in the United States, along with the Republican Party. The party's socially liberal and progressive platform is largely considered center-left in the U.S. political spectrum. The party has the lengthiest record of continuous...	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 Henry Moore Teller Henry Moore Teller was a U.S. politician. Secretary of the Interior between 1882 and 1885.-Biography:He served in the Senate and Cabinet for over thirty years, and was connected with the Free Silver question, beginning in 1880. During that time, he did much in and out of Congress with tongue and...	Colorado	March 4, 1901		Silver Republican Silver Republican Party The Silver Republican Party was a United States political faction active in the 1890s. It was so named because it split from the Republican Party over the issues of "Free Silver" and bimetallism. The main Republican Party supported the gold standard....	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...
Miles Poindexter Miles Poindexter Miles Poindexter was an American politician. As a Republican and later a Progressive, he served as a United States Representative and United States Senator.-Early life:Poindexter was born in Memphis, Tennessee...	Wisconsin	1913	63rd 63rd United States Congress - House of Representatives:Democratic : 291 Republican : 134Progressive : 9Independent : 1TOTAL members: 435-Senate:President of the Senate: Thomas R. MarshallPresident pro tempore: James P. Clarke-Senate:...	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Progressive Progressive Party (United States, 1912) The Progressive Party of 1912 was an American political party. It was formed after a split in the Republican Party between President William Howard Taft and former President Theodore Roosevelt....
	Wisconsin	1915	64th 64th United States Congress The Sixty-fourth United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, DC from March 4, 1915 to March 4, 1917, during the third and fourth...	Progressive Progressive Party (United States, 1912) The Progressive Party of 1912 was an American political party. It was formed after a split in the Republican Party between President William Howard Taft and former President Theodore Roosevelt....	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...
Robert M. La Follette, Jr. Robert M. La Follette, Jr. Robert Marion "Young Bob" La Follette, Jr. was an American senator from Wisconsin from 1925 to 1947, the son of Robert M. La Follette, Sr., the brother of Philip La Follette, and Fola La Follette, whose husband was the playwright George Middleton.- Early life:La Follette was born in Madison,...	Wisconsin	1935	74th 74th United States Congress -House:Also 2 Delegates, 3 Resident Commissioners-Senate:President of the Senate: John N. Garner President pro tempore: Key Pittman -Majority leadership:*Majority leader: Joseph T. Robinson...	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Progressive	Caucused with the Republicans; briefly returned before losing in 1946.
George Norris	Nebraska	1937	75th 75th United States Congress The Seventy-fifth United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, DC from January 3, 1937 to January 3, 1939, during the first two years...	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Independent
Henrik Shipstead Henrik Shipstead Henrik Shipstead was an American politician. He served in the United States Senate from March 4, 1923, to January 3, 1947, from the state of Minnesota in the 68th, 69th, 70th, 71st, 72nd, 73rd, 74th, 75th, 76th, 77th, 78th, and 79th Congresses...	Minnesota	1940	76th 76th United States Congress The Seventy-sixth United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, DC from January 3, 1939 to January 3, 1941, during the seventh and...	Farmer-Labor Minnesota Farmer-Labor Party The Minnesota Farmer–Labor Party was a political party in the United States state of Minnesota, the most successful and longest-lasting of the constituent elements of the national Farmer–Labor Party movement, which had a presence in other states...	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...
Wayne Morse Wayne Morse Wayne Lyman Morse was a politician and attorney from Oregon, United States, known for his proclivity for opposing his parties' leadership, and specifically for his opposition to the Vietnam War on constitutional grounds....	Oregon	1953	83rd 83rd United States Congress The Eighty-third United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, DC from January 3, 1953 to January 3, 1955, during the first two years...	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Independent
Wayne Morse Wayne Morse Wayne Lyman Morse was a politician and attorney from Oregon, United States, known for his proclivity for opposing his parties' leadership, and specifically for his opposition to the Vietnam War on constitutional grounds....	Oregon	February 17, 1955	84th 84th United States Congress The Eighty-fourth United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, DC from January 3, 1955 to January 3, 1957, during the third and...	Independent	Democratic Democratic Party (United States) The Democratic Party is one of two major contemporary political parties in the United States, along with the Republican Party. The party's socially liberal and progressive platform is largely considered center-left in the U.S. political spectrum. The party has the lengthiest record of continuous...
Strom Thurmond Strom Thurmond James Strom Thurmond was an American politician who served as a United States Senator. He also ran for the Presidency of the United States in 1948 as the segregationist States Rights Democratic Party candidate, receiving 2.4% of the popular vote and 39 electoral votes...	South Carolina	September 16, 1964	88th 88th United States Congress The Eighty-eighth United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, DC from January 3, 1963 to January 3, 1965, during the last year of...	Democratic Democratic Party (United States) The Democratic Party is one of two major contemporary political parties in the United States, along with the Republican Party. The party's socially liberal and progressive platform is largely considered center-left in the U.S. political spectrum. The party has the lengthiest record of continuous...	Republican
Harry F. Byrd, Jr. Harry F. Byrd, Jr. Harry Flood Byrd, Jr. is a retired American politician. He represented Virginia in the United States Senate from 1965 to 1983. He is most notable for leaving the Democratic Party in 1970 and becoming an Independent, although he continued to caucus with the Democrats. He is the son of Harry F....	Virginia	1970	91st 91st United States Congress The Ninety-first United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, DC from January 3, 1969 to January 3, 1971, during the first two years...	Democratic Democratic Party (United States) The Democratic Party is one of two major contemporary political parties in the United States, along with the Republican Party. The party's socially liberal and progressive platform is largely considered center-left in the U.S. political spectrum. The party has the lengthiest record of continuous...	Independent	Kept seniority, but did not caucus with the Democrats
Richard Shelby Richard Shelby Richard Craig Shelby is the senior U.S. Senator from Alabama. First elected to the Senate in 1986, he is the ranking member of the United States Senate Committee on Banking, Housing, and Urban Affairs and was its chairman from 2003 to 2007....	Alabama	November 9, 1994	103rd 103rd United States Congress - House of Representatives :- Leadership :- Senate :* President: Dan Quayle , until January 20, 1993** Al Gore , from January 20, 1993* President pro tempore: Robert Byrd - Majority leadership :* Majority Leader: George Mitchell...	Democratic Democratic Party (United States) The Democratic Party is one of two major contemporary political parties in the United States, along with the Republican Party. The party's socially liberal and progressive platform is largely considered center-left in the U.S. political spectrum. The party has the lengthiest record of continuous...	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...
Ben N. Campbell Ben Nighthorse Campbell Benjamin Nighthorse Campbell is an American politician. He was a U.S. Senator from Colorado from 1993 until 2005 and was during his tenure the only American Indian serving in the U.S. Congress. Campbell was a three term U.S. Representative from 1987 to 1993, when he was sworn into office as a...	Colorado	March 3, 1995	104th 104th United States Congress The One Hundred Fourth United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, DC from January 3, 1995 to January 3, 1997, during the third and...	Democratic Democratic Party (United States) The Democratic Party is one of two major contemporary political parties in the United States, along with the Republican Party. The party's socially liberal and progressive platform is largely considered center-left in the U.S. political spectrum. The party has the lengthiest record of continuous...	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...
Robert Smith Robert C. Smith Robert C. "Bob" Smith is an American politician who has served in both the United States House of Representatives and the Senate. He is a member of the Republican Party.-Early life:Smith was born in Trenton, New Jersey...	New Hampshire	July 13, 1999		Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Independent
	New Hampshire	November 1, 1999		Independent	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...
Jim Jeffords Jim Jeffords James Merrill "Jim" Jeffords is a former U.S. Senator from Vermont. He served as a Republican until 2001, when he left the party to become an independent. He retired from the Senate in 2006.-Background:...	Vermont	June 6, 2001	107th 107th United States Congress The One Hundred Seventh United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, D.C. from January 3, 2001 to January 3, 2003, during the final...	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Independent	Caucused with the Democrats
Joe Lieberman Joe Lieberman Joseph Isadore "Joe" Lieberman is the senior United States Senator from Connecticut. A former member of the Democratic Party, he was the party's nominee for Vice President in the 2000 election. Currently an independent, he remains closely affiliated with the party.Born in Stamford, Connecticut,...	Connecticut	2006	110th 110th United States Congress The One Hundred Tenth United States Congress was the meeting of the legislative branch of the United States federal government, between January 3, 2007, and January 3, 2009, during the last two years of the second term of President George W. Bush. It was composed of the Senate and the House of...	Democratic Democratic Party (United States) The Democratic Party is one of two major contemporary political parties in the United States, along with the Republican Party. The party's socially liberal and progressive platform is largely considered center-left in the U.S. political spectrum. The party has the lengthiest record of continuous...	Independent- Democrat	Caucuses with the Democrats
Arlen Specter Arlen Specter Arlen Specter is a former United States Senator from Pennsylvania. Specter is a Democrat, but was a Republican from 1965 until switching to the Democratic Party in 2009...	Pennsylvania	April 28, 2009	111th 111th United States Congress The One Hundred Eleventh United States Congress was the meeting of the legislative branch of the United States federal government from January 3, 2009 until January 3, 2011. It began during the last two weeks of the George W. Bush administration, with the remainder spanning the first two years of...	Republican Republican Party (United States) The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...	Democratic Democratic Party (United States) The Democratic Party is one of two major contemporary political parties in the United States, along with the Republican Party. The party's socially liberal and progressive platform is largely considered center-left in the U.S. political spectrum. The party has the lengthiest record of continuous...

See also