A
| Senator | Years | State | Party |
|---|---|---|---|
| Joseph Carter Abbott | 1868–1872 | North Carolina | Republican |
| James Abdnor | 1981–1987 | South Dakota | Republican |
| Hazel Abel | 1954 | Nebraska | Republican |
| James Abourezk | 1973–1979 | South Dakota | Democratic |
| Spencer Abraham | 1995–2001 | Michigan | Republican |
| John Adair | 1805–1806 | Kentucky | Democratic-Republican |
| Alva B. Adams | 1923–1924, 1933–1941 |
Colorado | Democratic |
| Brock Adams | 1987–1993 | Washington | Democratic |
| John Quincy Adams | 1803–1808 | Massachusetts | Federalist |
| Robert H. Adams | 1830 | Mississippi | Democratic |
| Stephen Adams | 1852–1857 | Mississippi | Democratic |
| George D. Aiken | 1941–1975 | Vermont | Republican |
| James L. Alcorn | 1871–1877 | Mississippi | Republican |
| Nelson W. Aldrich | 1881–1911 | Rhode Island | Republican |
| Russell A. Alger | 1902–1907 | Michigan | Republican |
| Wayne Allard | 1997–2009 | Colorado | Republican |
| J. Frank Allee | 1903–1907 | Delaware | Republican |
| George Allen | 2001–2007 | Virginia | Republican |
| Henry Justin Allen | 1929–1930 | Kansas | Republican |
| James B. Allen | 1969–1978 | Alabama | Democratic |
| John B. Allen | 1889–1893, 1893 |
Washington | Republican |
| Maryon Pittman Allen | 1978 | Alabama | Democratic |
| Philip Allen | 1853–1859 | Rhode Island | Democratic |
| William Allen | 1837–1849 | Ohio | Democratic |
| William V. Allen | 1893–1899, 1899–1901 |
Nebraska | Populist |
| William B. Allison | 1873–1908 | Iowa | Republican |
| Gordon L. Allott | 1955–1973 | Colorado | Republican |
| Adelbert Ames | 1870–1874 | Mississippi | Republican |
| Alexander O. Anderson | 1840–1841 | Tennessee | Democratic |
| Clinton P. Anderson | 1949–1973 | New Mexico | Democratic |
| Joseph Anderson | 1797–1815 | Tennessee | Democratic-Republican |
| Wendell Anderson | 1976–1978 | Minnesota | Democratic |
| Charles O. Andrews | 1936–1946 | Florida | Democratic |
| Mark Andrews | 1981–1987 | North Dakota | Republican |
| Levi Ankeny | 1903–1909 | Washington | Republican |
| Henry B. Anthony | 1859–1884 | Rhode Island | Republican |
| William S. Archer | 1841–1847 | Virginia | Whig |
| David H. Armstrong | 1877–1879 | Missouri | Democratic |
| John Armstrong, Jr. | 1800–1802, 1803–1804 |
New York | Democratic-Republican |
| William L. Armstrong | 1979–1991 | Colorado | Republican |
| Samuel G. Arnold | 1862–1863 | Rhode Island | Republican |
| John Ashcroft | 1995–2001 | Missouri | Republican |
| Chester Ashley | 1844–1848 | Arkansas | Democratic |
| Eli P. Ashmun | 1816–1818 | Massachusetts | Federalist |
| Henry F. Ashurst | 1912–1941 | Arizona | Democratic |
| David Rice Atchison | 1843–1855 | Missouri | Democratic |
| Charles G. Atherton | 1843–1849, 1853 |
New Hampshire | Democratic |
| Warren Austin | 1931–1946 | Vermont | Republican |
Read more about this topic: List Of Former United States Senators