| AK | Sr | Sen. Lisa Murkowski | Republican | N |
| AK | Sr | Sen. Ted Stevens (out of office) | Republican | N |
| AL | Jr | Sen. Jefferson Sessions III | Republican | N |
| AL | Sr | Sen. Richard Shelby | Republican | N |
| AR | Jr | Sen. Mark Pryor | Democratic | N |
| AR | Sr | Sen. Blanche Lincoln | Democratic | N |
| AZ | Jr | Sen. Jon Kyl | Republican | N |
| AZ | Sr | Sen. John McCain III | Republican | N |
| CA | Jr | Sen. Barbara Boxer | Democratic | Y |
| CA | Sr | Sen. Dianne Feinstein | Democratic | N |
| CO | Sr | Sen. Wayne Allard (out of office) | Republican | N |
| CO | Sr | Sen. Ken Salazar (out of office) | Democratic | N |
| CT | Jr | Sen. Joseph Lieberman | Independent Democrat | Y |
| CT | Sr | Sen. Christopher Dodd | Democratic | NV |
| DE | Sr | Sen. Thomas Carper | Democratic | N |
| DE | Sr | Sen. Joseph Biden Jr. (out of office) | Democratic | Y |
| FL | Jr | Sen. Melquiades Martinez (out of office) | Republican | N |
| FL | Sr | Sen. Bill Nelson Sr. | Democratic | Y |
| GA | Jr | Sen. John Isakson | Republican | N |
| GA | Sr | Sen. C. Saxby Chambliss | Republican | N |
| HI | Jr | Sen. Daniel Akaka Sr. | Democratic | Y |
| HI | Sr | Sen. Daniel Inouye | Democratic | Y |
| IA | Jr | Sen. Thomas Harkin | Democratic | Y |
| IA | Sr | Sen. Charles Grassley | Republican | N |
| ID | Sr | Sen. Larry Craig (out of office) | Republican | N |
| ID | Sr | Sen. Michael Crapo | Republican | N |
| IL | Jr | Sen. Barack Obama Jr. (out of office) | Democratic | Y |
| IL | Sr | Sen. Richard Durbin | Democratic | Y |
| IN | Jr | Sen. Evan Bayh | Democratic | Y |
| IN | Sr | Sen. Richard Lugar | Republican | N |
| KS | Jr | Sen. Pat Roberts | Republican | N |
| KS | Sr | Sen. Samuel Brownback | Republican | N |
| KY | Jr | Sen. Jim Bunning | Republican | N |
| KY | Sr | Sen. Mitch McConnell | Republican | N |
| LA | Jr | Sen. David Vitter | Republican | N |
| LA | Sr | Sen. Mary Landrieu | Democratic | Y |
| MA | Sr | Sen. Edward Kennedy Sr. (out of office) | Democratic | N |
| MA | Sr | Sen. John Kerry | Democratic | Y |
| MD | Jr | Sen. Benjamin Cardin | Democratic | N |
| MD | Sr | Sen. Barbara Mikulski | Democratic | N |
| ME | Jr | Sen. Susan Collins | Republican | N |
| ME | Sr | Sen. Olympia Snowe | Republican | N |
| MI | Jr | Sen. Debbie Stabenow | Democratic | Y |
| MI | Sr | Sen. Carl Levin | Democratic | Y |
| MN | Sr | Sen. Norm Coleman (out of office) | Republican | N |
| MN | Sr | Sen. Amy Klobuchar | Democratic/Farmer/Labor | Y |
| MO | Jr | Sen. Claire McCaskill | Democratic | Y |
| MO | Sr | Sen. Christopher Bond | Republican | N |
| MS | Jr | Sen. Chester Lott Sr. (out of office) | Republican | N |
| MS | Sr | Sen. Thad Cochran | Republican | N |
| MT | Jr | Sen. Jon Tester | Democratic | Y |
| MT | Sr | Sen. Max Baucus | Democratic | Y |
| NC | Sr | Sen. Richard Burr | Republican | N |
| NC | Sr | Sen. Elizabeth Dole (out of office) | Republican | N |
| ND | Jr | Sen. Byron Dorgan | Democratic-NPL | Y |
| ND | Sr | Sen. Kent Conrad | Democratic-NPL | Y |
| NE | Sr | Sen. Charles Hagel (out of office) | Republican | Y |
| NE | Sr | Sen. E. Benjamin Nelson | Democratic | Y |
| NH | Jr | Sen. John Sununu (out of office) | Republican | N |
| NH | Sr | Sen. Judd Gregg | Republican | N |
| NJ | Jr | Sen. Robert Menendez | Democratic | Y |
| NJ | Sr | Sen. Frank Lautenberg | Democratic | Y |
| NM | Sr | Sen. Pete Domenici (out of office) | Republican | N |
| NM | Sr | Sen. Jeff Bingaman | Democratic | Y |
| NV | Jr | Sen. John Ensign | Republican | N |
| NV | Sr | Sen. Harry Reid | Democratic | Y |
| NY | Jr | Sen. Hillary Clinton (out of office) | Democratic | Y |
| NY | Sr | Sen. Charles Schumer | Democratic | Y |
| OH | Jr | Sen. Sherrod Brown | Democratic | Y |
| OH | Sr | Sen. George Voinovich | Republican | N |
| OK | Jr | Sen. Thomas Coburn | Republican | N |
| OK | Sr | Sen. James Inhofe | Republican | N |
| OR | Jr | Sen. Gordon Smith (out of office) | Republican | N |
| OR | Sr | Sen. Ron Wyden | Democratic | Y |
| PA | Jr | Sen. Robert Casey Jr. | Democratic | Y |
| PA | Sr | Sen. Arlen Specter | Democratic | N |
| RI | Jr | Sen. Sheldon Whitehouse | Democratic | Y |
| RI | Sr | Sen. John Reed | Democratic | Y |
| SC | Jr | Sen. Jim DeMint | Republican | N |
| SC | Sr | Sen. Lindsey Graham | Republican | N |
| SD | Jr | Sen. John Thune | Republican | N |
| SD | Sr | Sen. Tim Johnson | Democratic | NV |
| TN | Jr | Sen. Bob Corker | Republican | N |
| TN | Sr | Sen. Lamar Alexander | Republican | N |
| TX | Jr | Sen. John Cornyn | Republican | N |
| TX | Sr | Sen. Kay Hutchison | Republican | N |
| UT | Jr | Sen. Robert Bennett | Republican | N |
| UT | Sr | Sen. Orrin Hatch | Republican | N |
| VA | Sr | Sen. John Warner (out of office) | Republican | N |
| VA | Sr | Sen. James Webb Jr. | Democratic | Y |
| VT | Jr | Sen. Bernard Sanders | Independent | Y |
| VT | Sr | Sen. Patrick Leahy | Democratic | Y |
| WA | Jr | Sen. Maria Cantwell | Democratic | Y |
| WA | Sr | Sen. Patty Murray | Democratic | Y |
| WI | Jr | Sen. Russell Feingold | Democratic | Y |
| WI | Sr | Sen. Herbert Kohl | Democratic | Y |
| WV | Jr | Sen. John Rockefeller IV | Democratic | Y |
| WV | Sr | Sen. Robert Byrd | Democratic | Y |
| WY | Sr | Sen. Michael Enzi | Republican | N |