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 orUnited States Senate, 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 |