The insurgent progressive movement jolting the Democratic Party rolled through Colorado on Tuesday evening in the latest test of the left’s ability to oust establishment politicians and usher in generational change.
In two primary battles between mainstream figures and candidates running to their left as Washington outsiders, the more liberal candidates prevailed. Melat Kiros, a 29-year-old lawyer and democratic socialist, toppled a veteran congresswoman in Denver, while Phil Weiser, the state attorney general, stopped Senator Michael Bennet’s bid to move from Congress to the governor’s mansion.
But in a third key primary race, Senator John Hickenlooper staved off a progressive challenger.
Here are five takeaways from the night in Colorado, where Democrats will be favored in all three races in November.
Even older progressives are falling to young left-wing challengers.
Representative Diana DeGette, who lost to Ms. Kiros, sported legitimate progressive credentials. She was a strong backer of “Medicare for all,” and she ran a television advertisement featuring prior praise from Representative Alexandria Ocasio-Cortez, who did not pick a side in Tuesday’s primary.
Nevertheless, she met her match in Ms. Kiros, who centered her campaign on calls for generational change — Ms. DeGette, 68, was first elected to Congress the year before Ms. Kiros, 29, was born — and on opposition to Israel over the war in Gaza.
Ms. DeGette said last year that she opposed the sale of “offensive weapons” to Israel, but in the past she had called herself a “strong supporter of Israel.” Ms. Kiros was far more outspoken in her opposition to the war and her calls to end U.S. military aid to Israel.
Socialists are racking up victories around the country.
Ms. Kiros adds to a growing number of socialist candidates expected to enter Congress next year, including Claire Valdez and Darializa Avila Chevalier of New York and Chris Rabb of Pennsylvania.
Running in a deep-blue Denver district, Ms. Kiros did not shy away from her socialist label. She welcomed support from the Democratic Socialists of America and Hasan Piker, a provocative left-wing livestreamer who is popular with young progressives but controversial with the party establishment.
Her victory is likely to further embolden the ascendant movement, which has aspirations beyond deep-blue cities.
In Wisconsin, a candidate for governor, Francesca Hong, will test whether socialism can appeal to voters in a swing state. And two battleground Senate candidates who do not identify as socialists but also have left-wing, populist politics — Abdul El-Sayed in Michigan and Graham Platner in Maine — are on similar missions.
One establishment veteran wasn’t caught flat-footed.
On the surface, Colorado’s Democratic primary for Senate mirrored the kinds of races that have been ripe for upset victories this year: A 74-year-old moderate incumbent who had spent 20 years in state politics faced a younger progressive who was once a D.S.A. member.
But toppling a U.S. senator in a statewide race remains considerably more difficult than ousting a House member, at least on the Democratic side. And Mr. Hickenlooper turned back his challenge from Julie Gonzales, a state senator, by nimbly moving to the left and drastically outspending her.
Mr. Hickenlooper focused his campaign pitch on liberal priorities like overhauling the Immigration and Customs Enforcement agency. He also earned some support from labor and activist groups, preventing Ms. Gonzales from consolidating progressives.
Perhaps most significantly, he raised nearly $8 million, while she had less than $1 million at her disposal.
Trump loomed large in an upset in the governor’s race.
Colorado’s other senator was not so fortunate.
Mr. Bennet lost his bid to become the state’s next governor to Mr. Weiser, who had trailed by 30 percentage points in polls last year but managed to make the race a referendum on how forcefully the two candidates were opposing President Trump.
Pointing to his lawsuits against the administration, and to Mr. Bennet’s votes to confirm a few of Mr. Trump’s cabinet members, Mr. Weiser won that metric.
And although Mr. Weiser does not profile as a typical insurgent progressive — he is a former federal lawyer who served in the Obama administration and as dean of a law school — he successfully portrayed himself as an outsider running to Mr. Bennet’s left.
Democrats keep picking progressives in key House races.
In swing districts from California to Pennsylvania this year, Democratic voters have bucked the conventional wisdom of running centrist candidates who can peel off independent voters against Republicans. Instead, they have backed left-wing candidates.
Coloradans took a similar approach on Tuesday, choosing Manny Rutinel, a progressive state lawmaker, over Shannon Bird, a more moderate legislator, in the Democratic primary race to face Representative Gabe Evans, a vulnerable Republican in a district north of Denver.
The general election will also be a test of whether Democrats can regain support from Latino voters. Mr. Rutinel, who is Dominican American, will need a sizable chunk of them in a district that is nearly 40 percent Latino to beat Mr. Evans, who is Mexican American.