The 2008 United States Senate election in Iowa was held on November 4, 2008. Incumbent Senator Tom Harkin sought re-election to a fifth 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 is the last time that a Democrat has won a U.S. Senate election in Iowa.

Democratic primary

Candidates

Results

Republican primary

Candidates

Results

[[File:2008 United States Senate Republican primary election in Iowa results map by county.svg|thumb|Republican primary results by county {{legend|#e27f7f|Reed}} {{legend|#ffc8cd|30–40%}} {{legend|#ffb2b2|40–50%}} {{legend|#e27f7f|50–60%}} {{legend|#5bc75b|Eichhorn}} {{legend|#aae5aa|30–40%}} {{legend|#87de87|40–50%}} {{legend|#5bc75b|50–60%}} {{legend|#309a30|70–80%}} {{legend|#ff7644|Rathje}} {{legend|#ffac8e|30–40%}} {{legend|#ff8e65|40–50%}} {{legend|#ff7644|50–60%}} ]]

General election

Predictions

Polling

Results

Counties that flipped from Republican to Democratic