1st Congressional District

Melat Kiros defeated Rep. Diana DeGette in Denver's 1st Congressional District primary with 53.2% of the vote, winning precincts across city center, west, and north Denver. Voter turnout in Denver's 2026 primary reached 40% of active voters, higher than 2024 and 2022 but similar to 2018. Phil Weiser won Denver's gubernatorial primary with 66% of the vote, while state Sen. Barbara Kirkmeyer led Republican primary support in Denver with 51%.

The Democratic Socialists of America (DSA) is targeting Colorado primaries following recent victories in New York. DSA-backed Melat Kiros is challenging Democratic Rep. Diana DeGette in Colorado's 1st Congressional District, with Justice Democrats also supporting Kiros. The primary is part of a broader effort by far-left candidates to challenge Democratic Party establishment figures.

Congresswoman Diana DeGette, who has represented Denver's 1st Congressional District for nearly 30 years, faces challenges from two Democratic candidates, Melat Kiros and Wanda James, in the June 30 primary. Republican Christy Peterson is unopposed in her party's primary, focusing on issues like public safety and manufacturing. Kiros emphasizes systemic change and community-driven governance, while DeGette remains a long-standing figure in Colorado politics.

Missouri voters approved a 2016 constitutional amendment banning new sales taxes on most services, but under proposed Amendment 4, it would have failed due to not securing a majority in each of Missouri's eight congressional districts. The 2016 measure passed statewide with 57% support but lost in the 1st Congressional District, meaning Amendment 4 would have blocked it and similar citizen-led initiatives.

Voters in South Carolina are casting ballots in House primary elections with two open seats. Reps. Nancy Mace of the 1st Congressional District and Ralph Norman of the 5th Congressional District are running for governor, leaving their seats vacant. Polls close at 7 p.m. EDT, with Decision Desk HQ providing live updates.

James Gallagher won a special election to claim a House seat in California's 1st Congressional District, boosting the GOP majority. He was endorsed by President Trump.

Montana voters are participating in the 2026 House primary elections. The 1st Congressional District is open due to Rep. Ryan Zinke retiring, with Democrats considering it a key target despite its red leanings. Troy Downing, a Republican, is running for reelection in the 2nd Congressional District.

Bucks County Commissioner Bob Harvie won the Democratic primary for Pennsylvania’s 1st Congressional District, defeating mathematician Lucia Simonelli. He will challenge five-term Republican U.S. Rep. Brian Fitzpatrick in the general election. The race was called by the Associated Press shortly after polls closed.

Republican Phil Berger, a Trump-endorsed North Carolina Senate leader, lost his primary election by 23 votes to Sheriff Sam Page. The close race highlights a rare setback for Trump's endorsement in a Republican-leaning district, creating a power vacuum in state politics.