Columns: State (linked to summaries below) | Senator | Party | Electoral history | Result | Candidates Winning candidate in bold
Arkansas | Mark Pryor | Democratic | 2002 | Incumbent re-elected | Mark Pryor (D) 79.5% Rebekah Kennedy (G) 20.5% | Delaware | Joe Biden | Democratic | 1972 1978 1984 1990 1996 2002 | Incumbent re-elected | Joe Biden (D) 64.7% Christine O'Donnell (R) 35.3% | Iowa | Tom Harkin | Democratic | 1984 1990 1996 2002 | Incumbent re-elected | Tom Harkin (D) 62.7% Christopher Reed (R) 37.3% | Kentucky | Mitch McConnell | Republican | 1984 1990 1996 2002 | Incumbent re-elected | Mitch McConnell (R) 53.0% Bruce Lunsford (D) 47.0% | Maine | Susan Collins | Republican | 1996 2002 | Incumbent re-elected | Susan Collins (R) 61.3% Tom Allen (D) 38.6% | Mississippi | Thad Cochran | Republican | 1978 1984 1990 1996 2002 | Incumbent re-elected | Thad Cochran (R) 61.4% Erik Fleming (D) 38.6% | Montana | Max Baucus | Democratic | 1978 1984 1990 1996 2002 | Incumbent re-elected | Max Baucus (D) 72.9% Bob Kelleher (R) 27.1% | New Mexico | Pete Domenici | Republican | 1972 1978 1984 1990 1996 2002 | Incumbent retired Democratic gain | Tom Udall (D) 61.3% Steve Pearce (R) 38.7% | Rhode Island | Jack Reed | Democratic | 1996 2002 | Incumbent re-elected | Jack Reed (D) 73.4% Robert Tingle (R) 26.6% | South Carolina | Lindsey Graham | Republican | 2002 | Incumbent re-elected | Lindsey Graham (R) 57.5% Bob Conley (D) 42.3% | South Dakota | Tim Johnson | Democratic | 1996 2002 | Incumbent re-elected | Tim Johnson (D) 62.5% Joel Dykstra (R) 37.5% | West Virginia | Jay Rockefeller | Democratic | 1984 1990 1996 2002 | Incumbent re-elected | Jay Rockefeller (D) 63.7% Jay Wolfe (R) 36.3%