The 2004 United States Senate election in Oregon was held on November 2, 2004. Incumbent Democratic U.S. Senator Ron Wyden won re-election to a second full term. As of 2025, this is the most recent United States Senate election in Oregon in which any Eastern Oregon counties voted for the Democratic nominee, and it is Oregon's most recent senatorial election in which the winning candidate carried the majority of the state's counties.

Democratic primary

Wyden was unopposed in the Democratic primary.

Republican primary

[[File: 2004 United States Senate election in Oregon, Republican primary.svg|thumb|Results by county King {{legend|#ffe0ea|20–30%}} {{legend|#ffc8cd|30–40%}} {{legend|#ffb2b2|40–50%}} {{legend|#e27f7f|50–60%}} Abshier {{legend|#ffdac1|20–30%}} Bowerman {{legend|#c0f0c0|20–30%}} ]]

General election

Predictions

Polling

Results

Counties that flipped from Democratic to Republican