The 2004 United States Senate election in Idaho took place on November 2, 2004, alongside other elections to the United States Senate in other states as well as elections to the United States House of Representatives and various state and local elections. Incumbent Republican Senator Mike Crapo ran for and won a second term in office in a landslide, as he was the only voting option besides a write-in campaign. Democrat Scott McClure conducted a write-in campaign but only received 4,136 votes, or 0.82% of those cast.

Republican primary

Candidates

Results

General election

Candidates

On ballot Write-in

Predictions

Results

[[File:2004 ID US Senate write-in Democratic vote.svg|thumb|150px|Support for Scott McClure Map legend {{legend|#37c871|≥4%}} {{legend|#87deaa|2–3%}} {{legend|#afe9c6|1–2%}} {{legend|#d7f4e3|<1%}} {{legend|#f2f2f2|No votes}} ]] Crapo won every county with over 90% of the vote. His weakest performance by far was in Democratic-leaning Latah County, where he got 95.6% of the vote to McClure's 4.4%.