Incumbent Ed Case (D), Della Au Belatti (D), Jarrett Keohokalole (D), and two other candidates are running in the Democratic primary for Hawaii's 1st Congressional District on August 8, 2026. The filing deadline is June 2, 2026. As of May 2026, Case, Belatti, and Keohokalole led in fundraising and local media attention.

Spectrum Local News' Michael Tsai said, "While it is relatively rare for an incumbent of Case’s standing to face significant opposition in the primary, Case has drawn fire from within his own party for voting in support of Republican initiatives, including ... the so-called SAVE Act, which requires documented proof of citizenship to register to vote." The Honolulu Star-Advertiser's Dan Nakaso said, "Both [University of Hawaii professor Colin] Moore and [political analyst Neal] Milner said Keohokalole and Belatti, who both consider themselves more left-leaning than Case, could split the progressive Democratic voters in the primary, making it easier for Case to win a plurality on Aug. 8." In the 2024 primary, Case defeated Cecil Hale (D) 92.0%–8.0%.

Case was first elected to the U.S. House in 2002. He ran unsuccessfully for the U.S. Senate in 2006 and was re-elected to the House in 2018. Case's campaign website says, "Our country and world face immense challenges that demand strong, smart leadership to defend our democracy and deliver real solutions. ... If re-elected, I will move to the top 25% of House seniority, continue on the powerful Appropriations Committee, and further expand my relationships and influence."

Belatti was elected to the Hawaii House of Representatives in 2006. She earlier worked as a teacher and an attorney. In a campaign ad, Belatti said, "[W]e've just seen an intensifying of a government that is rigged. A government that is serving corporate interests and not working families. I made a decision—and it was an easy decision—not to take corporate political action committee monies."

Keohokalole was elected to the Hawaii Senate in 2018. He was a member of the Hawaii House of Representatives from 2014 to 2018 and earlier worked as a legal fellow at the Hawaii Department of Land & Natural Resources. In a campaign ad, Keohokalole said, "The solutions we've been getting from Ed Case are not good enough. Families like mine are being priced out of our communities. Our kids have to leave to build a future and the help we need, the urgency we deserve, is missing."

Also running in the primary are Ben Fatula (D) and Perry Gregg (D).

As of May 2026, major forecasters rated the general election Solid/Safe Democratic. In 2024, Case defeated Patrick Largey (R) 71.8%– 28.2%.