Luke Bronin (D) defeated incumbent John Larson (D), Ruth Fortune (D), and Jillian Gilchrest (D) in the Democratic primary for Connecticut's 1st Congressional District on August 11, 2026. Larson, Bronin, and Gilchrest led in endorsements, fundraising, and local media attention.

At the May 2026 Democratic nominating convention, Larson, Bronin, and Gilchrest each received the 15% of the vote necessary to appear on the primary ballot. Bronin placed first with 51.2% of the vote in the final round.

The Hartford Courant's Christopher Keating said, "Bronin pulled off a stunning upset by defeating longtime U.S. Rep. John B. Larson at the Congressional convention." CT Insider's Dan Haar said, "Never in Connecticut's history, or so it is said, had a political party snubbed a sitting member of Congress vying to stay in office." The Connecticut Mirror's Mark Pazniokas and Lisa Hagen said Gilchrest "qualified for the primary ... with the help of Larson allies who prefer a three-way primary to a one-on-one fight with Bronin."

Bronin was an attorney, U.S. Navy Reserve veteran, and former member of President Barack Obama's (D) administration. He was mayor of Hartford from 2016 to 2024. Bronin said, "We need a bold, clear vision. And we need members of Congress who are out there every day building the political movement to make it possible. That’s why we need new energy, new ideas, and new perspectives in Washington – right now." VoteVets.org endorsed Bronin.

Larson was elected in 1998. He was a member of the Connecticut Senate from 1986 to 1998 and of the East Hartford Town Council from 1979 to 1983. Larson's campaign website said he had "delivered real results and real solutions on big issues – like infrastructure, and health care reform – and on local issues – helping over 17,500 constituents with problems involving veteran’s affairs, social security, immigration, and more." The American Israel Public Affairs Committee (AIPAC) endorsed Larson.

Gilchrest was elected to the Connecticut House of Representatives in 2018. She earlier worked as a social worker and nonprofit executive. Gilchrest completed Ballotpedia's Candidate Connection survey. In her survey response, Gilchrest said, "I am a social worker turned State Representative who has been effective in the State Legislature for the past 8 years. I am running to bring those skills down to Washington because our country is a mess right now." The Connecticut branch of Indivisible endorsed Gilchrest.

As of May 2026, major election forecasters rated the general election Solid/Safe Democratic. In 2024, Larson defeated Jim Griffin (R) 63.1%–34.8%.