The primaries on Tuesday in Colorado weren't a sweeping victory for the Democratic left like last week's in New York, where three very progressive candidates won, knocking out two incumbent members of Congress along the way. But the defeats of Representative Diana DeGette and Senator Michael Bennet in his gubernatorial bid and the strong challenge to incumbent Senator John Hickenlooper are the latest signs of a shift happening across the country: It's no longer enough for Democratic politicians to just vote the right way on key issues. The party base is looking for fighters and disrupters—and will cast aside solid politicians who they don't think will aggressively battle Donald Trump, MAGA, and right-wing billionaires.

Unlike New York, where there were three House candidates backed by Mayor Zohran Mamdani and effectively running as a slate, Colorado's primaries were more ideologically complicated. Melat Kiros, a democratic socialist who was backed by the Democratic Socialists of America, Senator Bernie Sanders, and other progressive leaders and groups both in Colorado and across the country, fairly easily defeated DeGette, who has represented the Denver area since 1997. Kiros will likely defeat the longtime incumbent by double digits, a result no one would have anticipated a few months ago.

State Senator Julie Gonzales, who was not endorsed by the DSA but had the support of many progressive groups in the state, lost to Hickenlooper but received more than 45 percent of the vote, an unusually high number when facing an incumbent senator.

Attorney General Phil Weiser won comfortably in the gubernatorial primary over Bennet, who had been considered the heavy front-runner until recently. Weiser isn't much more liberal than Bennet but positioned himself as more anti-Trump. He hammered Bennet for his votes to confirm several of Trump's executive branch nominees last year and won the backing of the state's Indivisible chapter.

It's normal to have multiple candidates seeking an open governorship (incumbent Jared Polis is term-limited), so Weiser's decision to take on Bennet wasn't unusual or surprising. But House Democratic incumbents rarely face strong primary challenges, and Democratic senators almost never do. And it's not as if Hickenlooper or DeGette are Joe Manchin–style centrists. They strongly backed Joe Biden's agenda and have opposed most of Trump's. DeGette is a member of the Congressional Progressive Caucus. While neither of them has been a leading critic of Israel, they haven't been vocally pro-Israel like Representative Dan Goldman, who was defeated last week in New York.

So why did DeGette and Hickenlooper get primary challengers, and why were those challenges so popular with voters? How did a man (Bennet) who has voted against nearly all of Trump's proposals in Washington lose a contest over who would be the most anti-Trump?

For the same reasons Mamdani won the Democratic primary in New York last year, Graham Platner won in Maine earlier this year, Abdul El-Sayed has surged in Michigan Senate polls, and other progressive candidates are gaining ground and winning around the country. Democratic voters are mad at party leaders for not defeating Trump in 2024 and then last year having to be coaxed by the base into aggressively opposing him. They are also curious if newer politicians will do a better job than those from the party establishment in fighting MAGA. Those two factors provide an opening for challenges to incumbents and front-runners, even those with fairly liberal voting records.

"A big difference in this race is, what's your approach to the Trump administration? Are you committed to fighting back, standing for our rights? Or, as Sen. Bennet has said, do you want to support some of these Trump administration Cabinet picks because you think maybe it'll get you a better relationship?" Weiser told Deseret News in a preelection interview.

I know there's a lot of talk about how Democratic voters increasingly like socialism and hate the Israeli government. The left-wing candidates have something of a playbook: Call for Medicare for All and abolishing Immigration and Customs Enforcement; declare what Israel has done in Gaza a genocide; bash the outsize role of billionaires and corporations in American politics.

But these primaries are not simply ideological referendums. Many insurgent candidates don't identify themselves as socialists or even progressives. The Denver DSA chapter is nowhere near as organized and powerful as the one in New York City. The Gaza war isn't a huge issue in some races that upstarts are winning, such as the Maine primary.

I suspect that Kiros (and New York's Claire Valdez and Darializa Avila Chevalier) won many voters who aren't die-hard democratic socialists but rather are traditional Democrats who want to see if a fresh face in Washington might be more effective than the kind of people they've been sending to Congress for a long time. And politicians like Hickenlooper, DeGette, and New York's Adriano Espaillat are vulnerable both because they have been in office for a long time and because they haven't been fighting the right in high-profile ways like Sanders or Senator Elizabeth Warren.

If you were trying to cast for traditional liberals who vote the right way on most issues but are entirely forgettable and rarely lead on progressive causes, it would be hard to choose a better trio than DeGette, Bennet, and Hickenlooper. In writing this article, I struggled to recall anything particularly good or bad that any of them had done on Capitol Hill. Do you remember that Bennet ran for president in 2020? I had forgotten.

My guess is that many liberals in very blue Denver feel they can have a representative like Alexandria Ocasio-Cortez, not just a progressive but a prominent, fiery one. In the run-up to the primary, DeGette emphasized her support for Medicare for All and abolishing ICE. But she hasn't been a high-profile advocate of those ideas—or really anything else.

"A scandal-free and reliably Democratic-voting incumbent losing in her primary basically for being too 'establishment' and not being strident enough against Republicans would strike me as an important moment, suggesting that what happened in New York last week is a national phenomenon," University of Denver political scientist Seth Masket wrote in his Substack newsletter on the eve of the election.

The boring normalness of Bennet, DeGette, and Hickenlooper (and the lack of Mamdani-like progressive presence) is why these primaries were so important. They are more representative of how the Democratic Party is changing than New York's races last week. The Democratic base is angry. Democratic politicians can channel that anger against Trump—or it will be channeled against them.