Colorado’s Democratic primaries on Tuesday produced several high-profile upsets and renewed debate over how the Democratic Party is changing ahead of the 2026 midterms. In Colorado’s 1st Congressional District, democratic socialist Melat Kiros defeated long-serving U.S. Rep. Diana DeGette, ending DeGette’s 15-term tenure representing the Denver area. The race is widely framed as part of a broader challenge to establishment figures within the party, following last week’s Democratic primaries in New York City in which several progressive challengers won.

Several sources describe Kiros’s support as coming from left-leaning organizers and national progressive figures, including backing tied to the Democratic Socialists of America and Sen. Bernie Sanders. The DeGette campaign is portrayed as losing with voters seeking more aggressive opposition to Republicans.

In statewide contests, Colorado’s attorney general Phil Weiser won the Democratic gubernatorial primary, defeating U.S. Sen. Michael Bennet, who had been viewed as the front-runner. Separately, Sen. John Hickenlooper defeated a challenge from state Sen. Julie Gonzales in the Democratic Senate primary, with polls described as competitive.

Taken together, the results are seen by outlets as evidence that anti-incumbent and anti-establishment themes are influencing Democratic primary voters, with implications for general-election matchups.