Third-party andindependent members of theUnited States Congress are generally rare. Although theRepublican andDemocratic parties have dominatedU.S. politics in atwo-party system since 1856, some independents and members of other political parties have also been elected to theHouse of Representatives orSenate, or changed their party affiliation during their term.
| Image | Senator | State | Term | Notes |
|---|---|---|---|---|
| Angus King | Maine | 2013–present | Elected as an independent; caucuses with the Democrats | |
| Bernie Sanders | Vermont | 2007–present | Elected as an independent;caucuses with the Democrats; Democratic Party member from 2015–2016 and 2019–2020 while running for President | |
| Joe Manchin | West Virginia | 2010–2025 | Elected as a Democrat, switched to independent in 2024[1] | |
| Kyrsten Sinema | Arizona | 2019–2025 | Elected as a Democrat, switched to independent in 2022[2] | |
| Joe Lieberman | Connecticut | 1989–2013 | Re-elected on theConnecticut for Lieberman ticket after losing the 2006 Democratic nomination | |
| Dean Barkley | Minnesota | 2002–2003 | Appointed forIndependence Party of Minnesota | |
| Jim Jeffords | Vermont | 1989–2007 | Switched from Republican to independent in 2001 | |
| Bob Smith | New Hampshire | 1990–2003 | Switched from Republican to independent in 1999 but switched back to Republican in 2000 | |
| James L. Buckley | New York | 1971–1977 | Elected as aConservative, lost re-election as a Republican in 1976 | |
| Harry F. Byrd Jr. | Virginia | 1965–1983 | Switched from Democratic to independent in 1970 | |
| Wayne Morse | Oregon | 1945–1969 | Switched from Republican to independent in 1953, then to Democratic in 1955 | |
| John E. Miller | Arkansas | 1937–1941 | Elected as an independent, served as Democratic | |
| Ernest Lundeen | Minnesota | 1937–1940 | Elected asFarmer-Labor | |
| George W. Norris | Nebraska | 1913–1943 | Switched from Republican to independent in 1936 | |
| Elmer Austin Benson | Minnesota | 1935–1936 | Elected asFarmer-Labor | |
| Robert M. La Follette Jr. | Wisconsin | 1925–1947 | Switched from Republican toProgressive in 1934, then back to Republican in 1946 | |
| Magnus Johnson | Minnesota | 1923–1925 | Elected asFarmer-Labor | |
| Henrik Shipstead | Minnesota | 1923–1947 | Elected asFarmer-Labor, switched to Republican in 1940 | |
| Miles Poindexter | Washington | 1911–1923 | Switched from Republican toProgressive in 1912, switched back to Republican in 1915 | |
| Joseph M. Dixon | Montana | 1907–1913 | Switched from Republican toProgressive in 1912 | |
| Henry Heitfeld | Idaho | 1897–1903 | Elected as aPopulist | |
| William Alexander Harris | Kansas | 1897–1903 | Elected as aPopulist | |
| Henry Moore Teller | Colorado | 1876–1909 | Switched from Republican toSilver Republican in 1896, then to Democratic in 1903 | |
| Fred Dubois | Idaho | 1891–1897 | Switched from Republican toSilver Republican in 1896 | |
| Frank J. Cannon | Utah | 1896–1899 | Switched from Republican toSilver Republican in 1896 | |
| Richard F. Pettigrew | South Dakota | 1889–1901 | Switched from Republican toSilver Republican in 1896 | |
| Lee Mantle | Montana | 1895–1899 | Switched from Republican toSilver Republican in 1896 | |
| John P. Jones | Nevada | 1873–1903 | Switched from Republican toSilver in 1895, then back to Republican in 1901 | |
| William Morris Stewart | Nevada | 1887–1905 | Switched from Republican toSilver in 1893, then back to Republican in 1901 | |
| William V. Allen | Nebraska | 1893–1901 | Elected as aPopulist | |
| James H. Kyle | South Dakota | 1891–1901 | Elected as aPopulist | |
| Marion Butler | North Carolina | 1895–1901 | Elected as aPopulist | |
| William A. Peffer | Kansas | 1891–1897 | Elected as aPopulist | |
| Harrison H. Riddleberger | Virginia | 1883–1889 | Elected as aReadjuster | |
| William Mahone | Virginia | 1881–1887 | Elected as aReadjuster | |
| David Davis | Illinois | 1877–1883 | Elected as an independent | |
| Newton Booth | California | 1875–1881 | Elected as anAnti-Monopolist, served as an Independent Republican | |
| Orris S. Ferry | Connecticut | 1867–1875 | Elected as aLiberal Republican in 1872 | |
| Morgan C. Hamilton | Texas | 1870–1877 | Switched from Republican toLiberal Republican in 1872, switched back to Republican in 1875 | |
| Charles Sumner | Massachusetts | 1851–1874 | Elected asFree Soil Democratic in 1851, became a Republican in 1855, then became aLiberal Republican in 1872 | |
| David T. Patterson | Tennessee | 1866–1869 | Elected as aUnionist in 1866, became a Republican by 1867 | |
| Joseph S. Fowler | Tennessee | 1866–1871 | Elected as anUnconditional Unionist in 1866, became a Republican by 1867 | |
| John Creswell | Maryland | 1865–1867 | Elected as anUnconditional Unionist in 1864 | |
| Benjamin Gratz Brown | Missouri | 1863–1867 | Elected as aUnion Emancipationist in 1863, became aRadical Unionist (Republican) by 1865 | |
| Peter G. Van Winkle | West Virginia | 1863–1869 | Elected as aUnionist in 1863, became a Republican by 1867 | |
| Reverdy Johnson | Maryland | 1863–1868 | Elected as aUnionist in 1863, switched to Democratic by 1865 | |
| Lemuel J. Bowden | Virginia | 1863–1864 | Elected as aUnionist in 1863 | |
| Thomas Holliday Hicks | Maryland | 1862–1865 | Elected as anUnconditional Unionist in 1862 | |
| Robert Wilson | Missouri | 1862–1863 | Appointed as aUnionist in 1862 | |
| John B. Henderson | Missouri | 1862–1869 | Elected as aUnionist in 1862, became a Republican by 1865 | |
| Garrett Davis | Kentucky | 1861–1872 | Elected as aUnion Democrat in 1861, switched to Democratic by 1867 | |
| John S. Carlile | Virginia | 1861–1865 | Elected as aUnionist in 1861 | |
| Waitman T. Willey | Virginia | 1861–1863 | Elected as aUnionist in 1861 |