| Term | Definition |
| Alaska | Mark Begich-D; Lisa Murkowski-R |
| Alabama | Jeff Sessions-R; Richard C. Shelby-R |
| Arkansas | Blanche L. Lincoln-D; Mark L. Pryor-D |
| Arizona | Jon Kyl-R; John McCain-R |
| California | Barbara Boxer-D; Dianne Feinstein-D |
| Colorado | Michael F. Bennet-D; Mark Udall-D |
| Connecticut | Christopher J. Dodd-D; Joseph I. Lieberman-ID |
| Delaware | Thomas R. Carper-D; Edward E. Kaufman-D |
| Florida | Mel Martinez-R; Bill Nelson-D |
| Georgia | Saxby Chambliss-R; Johnny Isakson-R |
| Hawaii | Daniel K. Akaka-D; Daniel K. Inouye-D |
| Iowa | Chick Grassley-R; Tom Harkin-D |
| Idaho | Mike Crapo-R; James E. Risch-R |
| Illinois | Roland W. Burris-D; Richard J. Durbin-D |
| Indiana | Evan Bayh-D; Richard G. Lugar-R |
| Kansas | Sam Brownback-R; Pat Roberts-R |
| Kentucky | Jim Bunning-R; Mitch McConnell-R |
| Louisiana | Mary L. Landriu-D; David Vitter-R |
| Massachusetts | Edward M. Kennedy-D; John F. Kerry-D |
| Maryland | Benjamin L. Cardin-D; Barbara A. Mikulski-D |
| Maine | Susan M. Collins-R; Olympia J. Snowe-R |
| Michigan | Carl Levin-D; Debbie Stabenow-D |
| Minnesota | Amy Klobuchar-D |
| Missouri | Christopher S. Bond-R; Claire McCaskill-D |
| Mississippi | Thad Cochran-R; Roger F. Wicker-R |
| Montana | Max Baucus-D; Jon Tester-D |
| North Carolina | Richard Burr-R; Kay R. Hagan-D |
| North Dakota | Kent Conrad-D; Byron L. Dorgan-D |
| Nebraska | Mike Johanns-R; Ben Nelson-D |
| New Hampshire | Judd Gregg-R; Jeanne Shaheen-D |
| New Jersey | Frank R. Lautenberg-D; Robert Menendez-D |
| New Mexico | Jeff Bingaman-D; Tom Udall-D |
| Nevada | John Ensign-R; Harry Reid-D |
| New York | Kirsten E. Gillibrand-D; Charles E. Schumer-D |
| Ohio | Sherrod Brown-D; George V. Voinovich-R |
| Oklahoma | Tom Coburn-R; James M. Inhofe-R |
| Oregon | Jeff Merkley-D; Ron Wyden-D |
| Pennsylvania | Robert P. Casey, Jr.-D; Arlen Specter-D |
| Rhode Island | Jack Reed-D; Sheldon Whitehouse-D |
| South Carolina | Jim DeMint-R; Lindsey Graham-R |
| South Dakota | Tim Johnson-D; John Thune-R |
| Tennessee | Lamar Alexander-R; Bob Corker-R |
| Texas | John Cornyn-R; Kay Bailey Hutchison-R |
| Utah | Robert F. Bennett-R; Orrin G. Hatch-R |
| Virginia | Mark R. Warner-D; Jim Webb-D |
| Vermont | Patrick J. Leahy-D; Bernard Sanders-I |
| Washington | Maria Cantwell-D; Patty Murray-D |
| Wisconsin | Russell D. Feingold-D; Herb Kohl-D |
| West Virginia | Robert C. Byrd-D; John D. Rockefeller, IV-D |
| Wyoming | John Barrasso-R; Michael B. Enzi-R |