As we've been noting of late, the Democrats have a problem: socialists are on the move. The latest - in a striking upset, democratic socialist Melat Kiros defeated 15-term U.S. Rep. Diana DeGette in Tuesday's Democratic primary for Colorado's 1st Congressional District. The victory extends a recent winning streak for the party's left wing and hands Republicans fresh ammunition heading into the fall campaign.

Kiros, a 29-year-old former attorney, defeated the 68-year-old incumbent who has represented the Denver-based seat since 1997. DeGette, a member of the Congressional Progressive Caucus, had long been viewed as secure in the solidly Democratic district. Kiros's win, backed by Sen. Bernie Sanders and the Democratic Socialists of America, came just one week after the DSA notched several high-profile primary victories in New York City.

The result is likely to intensify internal Democratic tensions. While party leaders sought to minimize last week's New York outcomes, Kiros's success in a Western swing state makes it harder to dismiss the pattern as a purely local phenomenon confined to deep-blue urban strongholds.

According to Axios, Dems are freaking out. 

Rep. Diana DeGette (D-Colo.) was a staunch progressive, not a moderate, these members are privately fuming. So why did she become a target of the left?

•     "One more case in the growing dynamic of performative politics," one House Democrat, speaking on the condition of anonymity to share candid analysis on the results, told Axios.
•     "Diana was an excellent representative with seniority — but the style of someone younger and more outspoken has become more attractive to that cohort of motivated urban left voters."
•     A senior House Democrat called the result a "wake-up call" for members of Congress

Kiros drew scrutiny during the campaign for a letter she wrote criticizing the view that calls for the elimination of Israel constitute antisemitism. Despite those comments, she built a strong coalition among younger, college-educated voters who have moved into the district in recent years. With most votes counted, she held a roughly four-point lead when major outlets called the race.

GOP strategists quickly framed the outcome as evidence that the party's left flank is expanding its influence beyond traditional strongholds, according to The Hill. A spokesperson for the House Republican campaign arm said the result showed "the socialist takeover of the Democrat Party is no longer confined to deep-blue strongholds," arguing it would complicate Democratic efforts to flip the House.

Other Anti-Incumbent Signals In Colorado

Voters delivered additional rebukes to establishment figures on Tuesday. In the Democratic primary for governor, state Attorney General Phil Weiser defeated U.S. Sen. Michael Bennet, who had been considered the early frontrunner. Weiser, while a mainstream Democrat, ran an insurgent-style campaign that emphasized his record of suing the Trump administration 66 times and criticized Bennet for confirming some of President Trump's Cabinet nominees. He also portrayed the senator as too aligned with wealthy donors.

Bennet will keep his Senate seat and faces re-election in 2028.

In the U.S. Senate primary, Sen. John Hickenlooper successfully turned back a challenge from progressive state Sen. Julie Gonzales.

General Election Landscape Takes Shape

Tuesday's results also clarified several November matchups that could affect control of the House.

• Colorado's 1st District: Kiros is now the heavy favorite to hold the safely Democratic seat for her party.
• Colorado's 8th District: The contest remains one of the most competitive in the country. Vulnerable Republican Rep. Gabe Evans will face state Rep. Manny Rutinel, who won the Democratic primary. Cook Political Report rates the suburban Denver seat a toss-up.
• Colorado's 5th District: Army veteran Jessica Killin won the Democratic nomination to challenge Republican Rep. Jeff Crank. The seat has trended left in recent presidential cycles, though it remains in Republican hands.

Democrats currently need a net gain of three seats to retake the House majority.

The Colorado results add to a growing body of evidence that primary voters in 2026 are rewarding candidates who position themselves as outsiders - whether on the left flank of the Democratic Party or as critics of Washington incumbents more broadly.

Colorado's results come on the heels of last week's Democratic primaries in New York City - which turned into a referendum on the Democratic Party itself. 

Three socialist-backed candidates, backed by New York City Mayor Zohran Mamdani, won their races. The Democratic establishment got slaughtered, and the man left holding the wreckage is House Minority Leader Rep. Hakeem Jeffries (D-NY).

Every candidate Jeffries backed went down. That alone would be a bad night. What made it worse was the scene at the victory party for socialist-backed winner Claire Valdez, where the crowd erupted in boos when Jeffries's image appeared on screen, then broke into a chant: "You're next," a clear sign that his leadership position won't protect him from being a target of the Democratic Socialists of America Party.