The Seventeenth Amendment to the Constitution (1913) established direct election of senators, as well as a means of filling vacant Senate seats. If a vacancy occurs due to a senator's death, resignation, or expulsion, the Seventeenth Amendment allows state legislatures to empower the governor to appoint a replacement to complete the term or to hold office until a special election can take place. There are a few exceptions to this rule. Some states require a special election to fill a vacancy. A few states require the governor to appoint a replacement of the same political party as the previous incumbent. The date when a senator appointed to fill a vacancy is succeeded by a senator elected to fill the remainder of the term depends on a number of factors.
For more information on how vacancies are filled read, U.S. Senate Vacancies: Contemporary Developments and Perspectives (CRS) (PDF) and the Senate Document The Term of Senator: When Does It Begin and End? (PDF).
The names of current senators appear in bold print.
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| Senator | Appointed Effective Date | Oath Date | Elected |
| Rienzi M. Johnston (D-TX) | Jan 4, 1913 | Jan 7, 1913 | Did not seek election. |
| John N. Heiskell (D-AR) | Jan 6, 1913 | Jan 9, 1913 | Did not seek election. |
| William S. West (D-GA) | Mar 2, 1914 | Mar 6, 1914 | Did not seek election. |
| Johnson N. Camden, Jr. (D-KY) | Jun 16, 1914 | Jun 18, 1914 | Yes, on November 3, 1914. |
| Thomas Taggart (D-IN) | Mar 20, 1916 | Mar 27, 1916 | No, was defeated on November 7, 1916. |
| Charles L. McNary (R-OR) | May 29, 1917 | June 8, 1917 | Yes, to full term beginning March 4, 1918. |
| Charles B. Henderson (D-NV) | Jan 12, 1918 | Jan 24, 1918 | Yes, on November 5, 1918. |
| John F. Nugent (D-ID) | Jan 22, 1918 | Jan 30, 1918 | Yes, on November 5, 1918. |
| David Baird (R-NJ) | Feb 23, 1918 | Mar 7, 1918 | Yes, on November 5, 1918. |
| Walter Guion (D-LA) | Apr 22, 1918 | Apr 24, 1918 | Did not seek election. |
| Xenophon P. Wilfley (D-MO) | Apr 30, 1918 | May 7, 1918 | No, did not win nomination. |
| Christie Benet (D-SC) | Jul 6, 1918 | Jul 8, 1918 | No, did not win nomination. |
| Irving W. Drew (R-NH) | Sep 2, 1918 | Sep 11, 1918 | Did not seek election. |
| George B. Martin (D-KY) | Sep 7, 1918 | Sep 17, 1918 | Did not seek election. |
| Carter Glass (D-VA) | Feb 2, 1919 | Feb 2, 1920 | Yes, on November 3, 1920. |
| Braxton B. Comer (D-AL) | Mar 5, 1920 | Mar 15, 1920 | Did not seek election. |
| Holm O. Bursum (R-NM) | Mar 11, 1921 | Apr 11, 1921 | Yes, on September 20, 1921. |
| Thomas C. du Pont (R-DE) | Jul 7, 1921 | Jul 26, 1921 | No, defeated on November 7, 1922, but was successfully elected in 1924. |
| William E. Crow (R-PA) | Oct 24, 1921 | Oct 24, 1921 | Died on August 2, 1922. |
| George W. Pepper (R-PA) | Jan 9, 1922 | Jan 10, 1922 | Yes, on Nov 7, 1922. |
| Charles A. Rawson (R-IA) | Feb 24, 1922 | Feb 24, 1922 | Did not seek election. |
| David A. Reed (R-PA) | Aug 8, 1922 | Aug 16, 1922 | Yes, on November 7, 1922. |
| Rebecca L. Felton (D-GA) | Oct 3, 1922 | Nov 21, 1922 | Did not seek election. |
| James Couzens (R-MI) | Nov 29, 1922 | Dec 7, 1922 | Yes, on November 4, 1924. |
| Alva B. Adams (D-CO) | May 17, 1923 | Dec 3, 1923 | No, defeated on November 4, 1924, but was successfully elected in 1932. |
| William M. Butler (R-MA) | Nov 13, 1924 | Dec 1, 1924 | No, defeated on November 2, 1926. |
| George H. Williams (R-MO) | May 25, 1925 | Dec 7, 1925 | No, defeated on November 2, 1926. |
| Arthur R. Robinson (R-IN) | Oct 20, 1925 | Dec 7, 1925 | Yes, on November 2, 1926. |
| Gerald P. Nye (R-ND) | Nov 14, 1925 | Jan 12, 1926 | Yes, on June 30, 1926. |
| David W. Stewart (R-IA) | Aug 7, 1926 | Nov 10, 1926 | Yes, on November 2, 1926. |
| Bronson M. Cutting (R-NM) | Dec 29, 1927 | Jan 4, 1928 | Yes, on November 6, 1928, to full term beginning Mar 4, 1929; was not a candidate for special election on the same date to fill remainder of the term ending March 3, 1929. |
| Arthur H. Vandenberg | Mar 31, 1928 | Apr 5, 1928 | Yes, on November 6, 1928. |
| Cyrus Locher (D-OH) | Apr 4, 1928 | Apr 16, 1928 | No, defeated for nomination. |
| John Thomas (R-ID) | Jun 30, 1928 | Dec 3, 1928 | Yes, on November 6, 1928. |
| Daniel O. Hastings (R-DE) | Dec 10, 1928 | Dec 13, 1928 | Yes, on Nov 4, 1930. |
| Henry J. Allen (R-KS) | Apr 1, 1929 | Apr 15, 1929 | No, defeated on November 4, 1930. |
| William E. Brock (D-TN) | Sep 2, 1929 | Sep 9, 1929 | Yes, on November 4, 1930. |
| Roscoe C. McCulloch (R-OH) | Nov 5, 1929 | Nov 12, 1929 | No, defeated on November 4, 1930. |
| David Baird, Jr. (R-NJ) | Nov 30, 1929 | Dec 9, 1929 | Did not seek election. |
| Patrick J. Sullivan (R-WY) | Dec 5, 1929 | Dec 9, 1929 | Did not seek election. |
| Joseph R. Grundy (R-PA) | Dec 11, 1929 | Dec 12, 1929 | No, defeated for nomination. |
| John Robsion (R-KY) | Jan 11, 1930 | Jan 11, 1930 | No, defeated on November 4, 1930. |
| Cameron A. Morrison (D-NC) | Dec 13, 1930 | Dec 17, 1930 | No, defeated for nomination. |
| Frank C. Partridge (R-VT) | Dec 23, 1930 | Jan 5, 1930 | No, defeated for nomination. |
| Hattie W. Caraway (D-AR) | Nov 13, 1931 | Dec 8, 1931 | Yes, on January 12, 1932. |
| William W. Barbour (R-NJ) | Dec 1, 1931 | Dec 8, 1931 | Yes, on November 8, 1932. |
| John S. Cohen (D-GA) | Apr 25, 1932 | Apr 27, 1932 | Did not seek election. |
| Walter Walker (D-CO) | Sep 26, 1932 | Dec 5, 1932 | No, defeated on November 8, 1932. |
| Elijah S. Grammer (R-WA) | Nov 22, 1932 | Dec 5, 1932 | Did not seek election. |
| Nathan L. Bachman (D-TN) | Mar 4, 1933 | Mar 4, 1933 | Yes, on November 6, 1934. |
| Harry F. Byrd (D-VA) | Mar 4, 1933 | Mar 4, 1933 | Yes, on November 7, 1933. |
| John E. Erickson (D-MT) | Mar 13, 1933 | Mar 16, 1933 | No, defeated for nomination. |
| William H. Thompson (D-NE) | May 24, 1933 | May 26, 1933 | Did not seek election. |
| Carl A. Hatch (D-NM) | Oct 10, 1933 | Jan 3, 1934 | Yes, on November 6, 1934. |
| Ernest W. Gibson (R-VT) | Nov 21, 1933 | Jan 3, 1934 | Yes, on January 16, 1934. |
| Joseph C. O'Mahoney (D-WY) | Jan 1, 1934 | Jan 3, 1934 | Yes, on November 6, 1934. |
| Dennis Chavez (D-NM) | May 11, 1935 | May 20, 1935 | Yes, on November 3, 1936. |
| Elmer A. Benson (Farmer Laborite-MN) | Dec 27, 1935 | Jan 3, 1936 | Did not seek election. |
| Rose M. Long (D-LA) | Jan 31, 1936 | Feb 10, 1936 | Yes, on April 21, 1936. |
| Scott M. Loftin (D-FL) | May 26, 1936 | May 27, 1936 | Did not seek election. |
| William L. Hill (D-FL) | Jul 1, 1936 | Jul 1, 1936 | Did not seek election. |
| Herbert E. Hitchcock (D-SD) | Dec 29, 1936 | Jan 1, 1937 | No, defeated for nomination. |
| George L. Berry (D-TN) | May 6, 1937 | May 10, 1937 | No, defeated for nomination. |
| Dixie B. Graves (D-AL) | Aug 19, 1937 | Aug 20, 1937 | Did not seek election. |
| J. Lister Hill (D-AL) | Jan 11, 1938 | Jan 11, 1938 | Yes, on April 26, 1938. |
| John G. Milton (D-NJ) | Jan 18, 1938 | Jan 24, 1938 | Did not seek election. |
| Alfred E. Reames (D-OR) | Feb 1, 1938 | Feb 11, 1938 | Did not seek election. |
| Thomas M. Storke (D-CA) | Nov 9, 1938 | -- | Did not seek election. |
| James M. Slattery (D-IL) | Apr 14, 1939 | Apr 24, 1939 | No, defeated on November 6, 1940. |
| Happy Chandler (D-KY) | Oct 10, 1939 | Oct 10, 1939 | Yes, on November 6, 1940. |
| John Thomas (R-ID) | Jan 27, 1940 | Feb 6, 1940 | Yes, on November 6, 1940. |
| Ernest W. Gibson, Jr. (R-VT) | Jun 24, 1940 | Jul 3, 1940 | Did not seek election. |
| Joseph H. Ball (R-MN) | Oct 14, 1940 | Oct 17, 1940 | Yes, on November 6, 1940, to full term beginning January 3, 1941. |
| Berkeley L. Bunker (D-NV) | Nov 27, 1940 | Dec 12, 1940 | No, defeated for nomination. |
| Joseph Rosier (D-WV) | Jan 13, 1941 | May 14, 1941 | No, defeated on November 17, 1942. |
| George L. Spencer (D-AR) | Apr 1, 1941 | Apr 2, 1941 | Did not seek election. |
| Andrew J. Houston (D-TX) | Apr 21, 1941 | Jun 2, 1941 | Died on June 26, 1941. |
| James O. Eastland (D-MS) | Jun 30, 1941 | Jun 30, 1941 | Did not seek election at this time, but was elected to the Senate in 1942. |
| Alva M. Lumpkin (D-SC) | Jul 22, 1941 | Jul 22, 1941 | No, died in office on August 1, 1941. |
| Roger C. Peace (D-SC) | Aug 5, 1941 | Aug 6, 1941 | Did not seek election. |
| Eugene D. Millikin (R-CO) | Dec 20, 1941 | Jan 5, 1942 | Yes, on November 3, 1942. |
| Arthur Walsh (D-NJ) | Nov 26, 1943 | Dec 2, 1943 | Did not seek election. |
| Samuel D. Jackson (D-IN) | Jan 28, 1944 | Jan 31, 1944 | Did not seek election. |
| Sinclair Weeks (R-MA) | Feb 8, 1944 | Feb 15, 1944 | Did not seek election. |
| Guy Cordon (R-OR) | Mar 4, 1944 | Mar 13, 1944 | Yes, on November 8, 1944. |
| Wilton E. Hall (D-SC) | Nov 20, 1944 | Nov 27, 1944 | Did not seek election. |
| Hugh B. Mitchell (D-WA) | Jan 10, 1945 | Jan 18, 1945 | No, defeated on November 5, 1946. |
| Frank P. Briggs (D-MO) | Jan 18, 1945 | Jan 22, 1945 | No, defeated on November 5, 1946. |
| Thomas C. Hart (R-CT) | Feb 15, 1945 | Feb 15, 1945 | Did not seek election. |
| Milton R. Young (R-ND) | Mar 12, 1945 | Mar 19, 1945 | Yes, on June 25, 1946. |
| Edward P. Carville (D-NV) | Jul 24, 1945 | Jul 26, 1945 | No, defeated for nomination. |
| William F. Knowland (R-CA) | Aug 26, 1945 | Sep 5, 1945 | Yes, on November 5, 1946. |
| James W. Huffman (D-OH) | Oct 8, 1945 | Oct 9, 1945 | No, defeated on November 5, 1946. |
| Charles C. Gossett (D-ID) | Nov 17, 1945 | Nov 29, 1945 | No, defeated for nomination. |
| William A. Stanfill (R-KY) | Nov 19, 1945 | Nov 23, 1945 | Did not seek election. |
| Thomas G. Burch (D-VA) | May 31, 1946 | May 31, 1946 | Did not seek election. |
| George R. Swift (D-AL) | Jun 15, 1946 | Jun 20, 1946 | Did not seek election. |
| Spessard L. Holland (D-FL) | Sep 25, 1946 | -- | Yes, on November 5, 1946. |
| Ralph E. Flanders (R-VT) | Nov 1, 1946 | Jan 1, 1947 | Yes, on November 5, 1946. |
| William B. Umstead (D-NC) | Dec 18, 1946 | Jan 1, 1947 | No, defeated for nomination. |
| William C. Feazel (D-LA) | May 18, 1948 | May 24, 1948 | Did not seek election. |
| Vera C. Bushfield (R-SD) | Oct 6, 1948 | -- | Did not seek election. |
| Garrett L. Withers (D-KY) | Jan 20, 1949 | Jan 20, 1949 | Did not seek election. |
| Frank P. Graham (D-NC) | Mar 23, 1949 | Mar 29, 1949 | No, defeated for nomination. |
| John F. Dulles (R-NY) | Jul 7, 1949 | Jul 8, 1949 | No, defeated on November 8, 1949. |
| Edward L. Leahy (D-RI) | Aug 23, 1949 | Aug 24, 1949 | Did not seek election. |
| Henry C. Dworshak (R-ID) | Oct 14, 1949 | Oct 15, 1949 | Yes, on November 7, 1950. |
| Harry Darby (R-KS) | Dec 1, 1949 | Jan 3, 1950 | Did not seek election. |
| William Benton (D-CT) | Dec 17, 1949 | Jan 3, 1950 | Yes, on November 7, 1950. |
| Thomas R. Underwood (D-KY) | Mar 19, 1951 | Mar 19, 1951 | No, defeated on November 4, 1952. |
| Arthur E. B. Moody (D-MI) | Apr 23, 1951 | Apr 25, 1951 | No, defeated on November 4, 1952. |
| Frederick A. Seaton (R-NE) | Dec 10, 1951 | Jan 8, 1952 | Did not seek election. |
| William A. Purtell (R-CT) | Aug 29, 1952 | Jan 3, 1953 | Was not a candidate in special election to fill remainer of the term to which he was appointed, but was elected to Class I seat in 1952. |
| Thomas H. Kuchel (R-CA) | Jan 2, 1953 | Jan 3, 1953 | Yes, on November 2, 1954. |
| Alton A. Lennon (D-NC) | Jul 10, 1953 | Jul 15, 1953 | No, defeated for nomination. |
| Robert W. Upton (R-NH) | Aug 14, 1953 | Jan 6, 1954 | No, defeated for nomination. |
| Thomas A. Burke (D-OH) | Nov 10, 1953 | Jan 6, 1954 | No, defeated on November 2, 1954. |
| Eva K. Bowring (R-NE) | Apr 16, 1954 | Apr 26, 1954 | Did not seek election. |
| Samuel J. Ervin, Jr. (D-NC) | Jun 5, 1954 | Jun 11, 1954 | Yes, on November 2, 1954. |
| Edward D. Crippa (R-WY) | Jun 24, 1954 | Jun 28, 1954 | Did not seek election. |
| Samuel W. Reynolds (R-NE) | Jul 3, 1954 | Jul 7, 1954 | Did not seek election. |
| Charles E. Daniel (D-SC) | Sep 6, 1954 | Nov 8, 1954 | Did not seek election. |
| Ernest S. Brown (R-NV) | Oct 1, 1954 | Nov 8, 1954 | No, defeated on November 2, 1954. |
| William R. Laird III (D-WV) | Mar 13, 1956 | Mar 15, 1956 | Did not seek election. |
| Thomas A. Wofford (D-SC) | Apr 5, 1956 | Apr 9, 1956 | Did not seek election. |
| Robert Humphreys (D-KY) | Jun 21, 1956 | Jun 25, 1956 | Did not seek election. |
| William A. Blakley (D-TX) | Jan 15, 1957 | Jan 17, 1957 | Did not seek election. |
| John D. Hoblitzell, Jr. (R-WV) | Jan 25, 1958 | Jan 27, 1958 | No, defeated on November 4, 1958. |
| Benjamin E. Jordan (D-NC) | Apr 19, 1958 | May 5, 1958 | Yes, on November 4, 1958. |
| Clarence Norman Brunsdale (R-ND) | Nov 19, 1959 | Nov 19, 1959 | Did not seek election. |
| Hall S. Lusk (D-OR) | Mar 16, 1960 | Mar 23, 1960 | Did not seek election. |
| Edward V. Long (D-MO) | Sep 23, 1960 | Jan 3, 1961 | Yes, on November 8, 1960. |
| Benjamin A. Smith II (D-MA) | Dec 27, 1960 | Jan 3, 1961 | Did not seek election. |
| William A. Blakley (D-TX) | Jan 3, 1961 | Jan 3, 1961 | No, defeated on May 27, 1961. |
| John J. Hickey (D-WY) | Jan 3, 1961 | Jan 3, 1961 | No, defeated on November 6, 1962. |
| Maurice J. Murphy, Jr. (R-NH) | Dec 7, 1961 | Jan 10, 1962 | No, defeated for nomination. |
| James B. Pearson (R-KS) | Jan 31, 1962 | Feb 5, 1962 | Yes, on November 6, 1962 |
| Joseph H. Bottum (R-SD) | Jul 9, 1962 | Jul 11, 1962 | No, defeated on November 6, 1962. |
| Len Jordan (R-ID) | Aug 6, 1962 | -- | Yes, on November 6, 1962. |
| Edwin L. Mechem (R-NM) | Nov 30, 1962 | Jan 1, 1963 | No, defeated on November 3, 1964. |
| James H. Edmondson (D-OK) | Jan 7, 1963 | Jan 9, 1963 | No, defeated for nomination. |
| Herbert S. Walters (D-TN) | Aug 20, 1963 | Aug 27, 1963 | Did not seek election. |
| Pierre E. G. Salinger (D-CA) | Aug 4, 1964 | Aug 5, 1964 | No, defeated on November 3, 1964. |
| Walter F. Mondale (D-MN) | Dec 30, 1964 | Jan 4, 1965 | Yes, on November 8, 1966. |
| Donald S. Russell (D-SC) | Apr 22, 1965 | Apr 23, 1965 | No, defeated for nomination. |
| Harry F. Byrd, Jr. (D, I-VA) | Nov 12, 1965 | Jan 10, 1965 | Yes, on November 8, 1966 |
| Robert P. Griffin (R-MI) | May 11, 1966 | May 16, 1966 | Yes, on November 8, 1966. |
| Charles E. Goodell (R-NY) | Sep 10, 1968 | Sep 12, 1968 | No, defeated on November 3, 1970. |
| Ted Stevens (R-AK) | Dec 24, 1968 | Jan 3, 1969 | Yes, on November 3, 1970. |
| Ralph T. Smith (R-IL) | Sep 17, 1969 | Sep 18, 1969 | No, defeated on November 3, 1970. |
| David H. Gambrell (D-GA) | Feb 1, 1971 | Feb 2, 1971 | No, defeated for nomination. |
| Robert T. Stafford (R-VT) | Sep 16, 1971 | Sep 17, 1971 | Yes, on January 7, 1972. |
| Elaine S. Edwards (D-LA) | Aug 1, 1972 | Aug 7, 1972 | Did not seek election. |
| Howard M. Metzenbaum (D-OH) | Jan 4, 1974 | Jan 21, 1974 | No, defeated for nomination, but was successfully elected to the Senate in 1976. |
| Louis C. Wyman (R-NH) | Dec 31, 1974 | -- | No, defeated on September 16, 1975. |
| Norris H. Cotton (R-NH) | Aug 8, 1975 | Sep 3, 1975 | Did not seek election. |
| Wendell R. Anderson (D-MN) | Dec 30, 1976 | Jan 4, 1977 | No, defeated on November 7, 1978. |
| Kaneaster Hodges, Jr. (D-AR) | Dec 10, 1977 | Dec 15, 1977 | Did not seek election. |
| Paul G. Hatfield (D-MT) | Jan 22, 1978 | Jan 23, 1978 | No, defeated for nomination. |
| Muriel B. Humphrey (D-MN) | Jan 25, 1978 | Feb 6, 1978 | Did not seek election. |
| Maryon P. Allen (D-AL) | Jun 8, 1978 | Jun 12, 1978 | No, defeated for nomination. |
| George J. Mitchell (D-ME) | May 17, 1980 | May 19, 1980 | Yes, on November 2, 1982. |
| Nicholas F. Brady (R-NJ) | Apr 12, 1982 | Apr 20, 1982 | Did not seek election. |
| Daniel J. Evans (R-WA) | Sep 8, 1983 | Sep 12, 1983 | Yes, on November 8, 1983. |
| James T. Broyhill (R-NC) | Jul 14, 1986 | Jul 17, 1985 | No, defeated on November 5, 1986. |
| David K. Karnes (R-NE) | Mar 11, 1987 | Mar 13, 1987 | No, defeated on November 8, 1988. |
| Daniel R. Coats (R-IN) | Jan 3, 1989 | Jan 3, 1989 | Yes, on November 6, 1990. |
| Daniel K. Akaka (D-HI) | May 16, 1990 | May 16, 1990 | Yes, on November 6, 1990. |
| John Seymour (R-CA) | Jan 7, 1991 | Jan 10, 1991 | No, defeated on November 3, 1992. |
| Harris Wofford (D-PA) | May 8, 1991 | May 9, 1991 | Yes, on November 5, 1991. |
| Jocelyn B. Burdick (D-ND) | Sep 12, 1992 | Sep 16, 1992 | Did not seek election. |
| Byron L. Dorgan (D-ND) | Dec 14, 1992 | -- | Did not seek election. |
| Harlan Mathews (D-TN) | Jan 2, 1993 | Jan 5, 1993 | Did not seek election. |
| Robert C. Krueger (D-TX) | Jan 21, 1993 | Jan 21, 1993 | No, defeated on June 5, 1993. |
| Sheila Frahm (R-KS) | Jun 11, 1996 | Jun 11, 1996 | No, defeated for nomination. |
| Lincoln D. Chafee (R-RI) | Nov 2, 1999 | Nov 4, 1999 | Yes, on November 7, 2000. |
| Zell B. Miller (D-GA) | Jul 24, 2000 | Jul 27, 2000 | Yes, on November 7, 2000. |
| Jean Carnahan (D-MO) | Jan 3, 2001 | Jan 3, 2001 | No, defeated on November 5, 2002. |
| Dean Barkley (IPM-MN) | Nov 4, 2002 | Nov 5, 2002 | Did not seek election. |
| Lisa Murkowski (R-AK) | Dec 20, 2002 | Jan 7, 2003 | Yes, on November 2, 2004. |
| Robert Menendez (D-NJ) | Jan 17, 2006 | Jan 18, 2006 | Yes, on November 7, 2006. |
| John Barrasso (R-WY) | Jun 22, 2007 | Jun 25, 2007 | Yes, on November 4, 2008. |
| Roger F. Wicker (R-MS) | Dec 31, 2007 | Dec 31, 2007 | Yes, on November 4, 2008. |
| Roland Burris (D-IL) | Jan 12, 2009 | Jan 15, 2009 | Did not seek election. |
| Ted Kaufman (D-DE) | Jan 15, 2009 | Jan 16, 2009 | Did not seek election. |
| Michael F. Bennet (D-CO) | Jan 21, 2009 | Jan 22, 2009 | Yes, on November 2, 2010. |
| Kirsten E. Gillibrand (D-NY) | Jan 26, 2009 | Jan 27, 2009 | Yes, on November 2, 2010. |
| George S. LeMieux (R-FL) | Sep 9, 2009 | Sep 10, 2009 | Did not seek election. |
| Paul G. Kirk, Jr. (D-MA) | Sep 24, 2009 | Sep 25, 2009 | Did not seek election. |
| Carte P. Goodwin (D-WV) | Jul 16, 2010 | Jul 20, 2010 | Did not seek election. |
| Dean Heller (R-NV) | May 9, 2011 | May 9, 2011 | Yes, on November 6, 2012. |
| Brian Schatz (D-HI) | Dec 26, 2012 | Dec 27, 2012 | Yes, on November 4, 2014. |
| Tim Scott (R-SC) | Jan 2, 2013 | Jan 3, 2013 | Yes, on November 4, 2014. |
| William Cowan (Mo) (D-MA) | Feb 1, 2013 | Feb 7, 2013 | Did not seek election. |
| Jeffrey S. Chiesa (R-NJ) | Jun 6, 2013 | Jun 10, 2013 | Did not seek election. |
| John E. Walsh (D-MT) | Feb 9, 2014 | Feb 11, 2014 | Did not seek election. |
| Luther J. Strange III (R-AL) | Feb 9, 2017 | Feb 9, 2017 | Not a candidate in the general election, having been defeated in a primary runoff election on September 26, 2017. |
| Tina Smith (D-MN) | Jan 3, 2018 | Jan 3, 2018 | Yes, on November 6, 2018. |
| Cindy Hyde-Smith (R-MS) | Apr 2, 2018 | Apr 9, 2018 | Yes, in a run-off election on November 27, 2018. |
| Jon L. Kyl (R-AZ) | Sep 4, 2018 | Sep 5, 2018 | Did not seek election. |
| Martha McSally (R-AZ) | Jan 3, 2019 | Jan 3, 2019 | No, defeated on November 3, 2020. |
| Kelly Loeffler (R-GA) | Jan 1, 2020 | Jan 6, 2020 | No, defeated on January 5, 2021. |
| Alex Padilla (D-CA) | Jan 18, 2021 | Jan 20, 2021 | Yes, on November 8, 2022. |
| Pete Ricketts (R-NE) | Jan 12, 2023 | Jan 23, 2023 | -- |
| Laphonza R. Butler (D-CA) | Oct 1, 2023 | Oct 3, 2023 | -- |
| George S. Helmy (D-NJ) | Aug 23, 2024 | Sep 9, 2024 | -- |