Colorado's primary day doubled as a stress test for the Democratic Party's establishment wing.

What's on the ballot

Voters were deciding nominees for governor, U.S. Senate, all eight U.S. House seats and statewide offices, with polls set to close at 7 p.m. local time, the Colorado Sun reported. As of this report, ballots were still being counted and no races had been called. The contests drew national attention as a test of whether the progressive momentum visible in recent Democratic primaries elsewhere — including New York City — could carry into a Western swing state, ABC News reported.

The Senate race

First-term Sen. John Hickenlooper, the former Denver mayor and governor, faced a Democratic challenge from his left in state Sen. Julie Gonzales, who campaigned on Medicare for All, housing and sharper criticism of corporate influence and U.S. policy on Israel. On the Republican side, state Sen. Mark Baisley ran unopposed. The Cook Political Report rates the seat "Solid D," meaning the Democratic nominee enters the fall as a strong favorite.

The open governorship

With Gov. Jared Polis term-limited, two prominent Democrats — U.S. Sen. Michael Bennet and state Attorney General Phil Weiser — competed for the nomination to succeed him, Al Jazeera reported. Weiser outraised Bennet in the contest, and a pre-election internal poll showed him ahead, though the race had not been called. Were Bennet to win the nomination and the governorship, it would eventually open his U.S. Senate seat, which he has said he would fill with an interim appointment.

The marquee House primary

The most-watched House contest was in Denver's heavily Democratic 1st District, where longtime Rep. Diana DeGette faced Melat Kiros, a 29-year-old attorney and democratic socialist endorsed by Sen. Bernie Sanders and backed by the group Justice Democrats. Outside spending in the race ran into the millions, reflecting a broader pattern: pro-Israel groups and establishment-aligned committees poured money into several Colorado primaries, while the organized left mounted door-knocking and ad campaigns for challengers. Elsewhere, the 8th District — the state's only seat rated a November toss-up — featured a competitive Democratic primary to take on the Republican incumbent.

Why it matters

Beyond Colorado, the results were expected to offer early evidence of where the Democratic electorate is heading — whether incumbents backed by heavy outside spending can fend off challengers running on health care, housing, corporate power and foreign policy. With counting still underway, the answers were not yet in; the Herald will report results as races are called.