Hawaii held its primary on Saturday, September 23. The Republican primary for U.S. Senate had six candidates. The winner, Gerald Coffee, had already withdrawn from the race, but his name had remained on the ballot. This means the Republican Party state committee will be able to choose a replacement nominee. The Democratic nominee is incumbent U.S. Senator Daniel Akaka, who defeated Democratic U.S. House member Ed Case.

The U.S. Senate race will be a 3-candidate race. The third candidate will be Libertarian Lloyd Mallan. An independent candidate for U.S. Senate, C. Kaul Jochanan, failed to qualify. Independent candidates in Hawaii (except for president) cannot appear on the November ballot unless they outpoll one of the partisan primary winners, or unless they poll 10% of the vote for that office in all primaries combined. Since Mallan received 209 votes in the Libertarian primary, and Jochanan only received 167 votes in the non-partisan primary, Jochanan cannot qualify.