The 2008 United States Senate election in Iowa was held on November 4, 2008. Incumbent Senator Tom Harkin sought re-election to a fifth and final term in office. Unlike Harkin's three previous reelection bids, he was not challenged by a sitting United States congressman, but instead faced small businessman Christopher Reed, who won the Republican primary by just a few hundred votes. Harkin defeated Reed in a landslide, winning 94 of Iowa's 99 counties. This was the last time a Democrat won a U.S. Senate election in Iowa until 2026.
Democratic primary
Candidates
- Tom Harkin, incumbent U.S. senator
Republican primary
Candidates
- George Eichhorn, former Iowa state representative
- Steve Rathje, construction company executive
- Christopher Reed, small businessman
General election
Results
Counties that flipped from Republican to Democratic
- Butler (largest city: Parkersburg)
- Crawford (largest city: Denison)
- Delaware (largest city: Manchester)
- Van Buren (largest city: Keosauqua)
- Plymouth (largest city: Le Mars)
- Grundy (largest city: Grundy Center)
- Harrison (largest city: Missouri Valley)
- Cass (largest city: Atlantic)
- Ida (largest city: Ida Grove)
- Fremont (largest city: Sidney)
- Pottawattamie (largest city: Council Bluffs)
- Sac (largest city: Sac City)
- Shelby (largest city: Harlan)
- Marion (largest city: Pella)
- Mills (largest city: Glenwood)
- Montgomery (largest city: Red Oak)
- Mahaska (largest city: Oskaloosa)
By congressional district
Harkin won all five congressional districts, including two that elected Republicans.