In the equivalent of a political earthquake, 29-year-old Democratic socialist Melat Kiros jumped into an early lead over 15-term U.S. Rep. Diana DeGette in Colorado’s Denver-based 1st Congressional District primary, according to initial returns posted Tuesday night.

In the first round of results, posted at 7 p.m., Kiros secured 47.49% of the vote to DeGette’s 45.15%. University of Colorado Regent Wanda James, a Navy veteran and the first Black owner of a cannabis dispensary, trailed with 7.36%.

Kiros held on to her lead, expanding it slightly by getting 49%, when the next batch of ballots were tallied about an hour later. DeGette’s count dropped to 44,%, with James trailing at 7%.

Election officials cautioned that Election Day turnout was unusually heavy, so it could take longer than usual to tally the ballots.

DeGette, a former state lawmaker and civil rights lawyer who was first elected to the district in 1996, is facing the toughest reelection challenge of her career as Kiros, a political newcomer and first-time candidate, seeks to capitalize on upsets scored by fellow socialists across the country in recent weeks.

Kiros, a former corporate attorney who immigrated from Ethiopia to the United States with her parents when she was an infant, declared her candidacy last year

The heavily Democratic seat, which nearly coincides with Denver’s footprint, hasn’t sent a Republican to Congress since 1970. In the decades since, it’s been represented by just two lawmakers, Democrats Pat Schroeder and DeGette, marking the longest stretch in the country’s history that any congressional district has been represented by women.

That won’t change after this year’s election, though a DeGette loss would also go down in the books. In the last 50 years, only one House incumbent has lost a bid for reelection in a Colorado primary, in 2020, when Republican Lauren Boebert unseated five-term U.S. Rep. Scott Tipton in the 3rd Congressional District.

Although Kiros landed top-line designation on the primary ballot at the Democrats’ district assembly in April — coming within a handful of delegate votes of keeping the incumbent off the ballot — DeGette’s allies began sounding the alarm earlier this month when internal polling reportedly showed DeGette leading Kiros within the margin of error.

In the weeks since ballots went out, outside groups have poured millions into advertising, mostly attacking Kiros by trying to tie her to some of DSA’s more unusual positions, including abolishing the U.S. Senate, pulling the United States out of NATO and essentially abolishing law enforcement.

Kiros said earlier this month at a candidate forum sponsored by Colorado Politics and the Denver Press Club that she didn’t agree with those provisions in the recently adopted DSA platform, but said her campaign was focused on fighting for working people, making Denver more affordable, and battling government corruption.

While she hasn’t enjoyed the level of outside spending that’s buoyed DeGette, Kiros has benefited from a surge of DSA enthusiasm after its aligned candidates defeated two House Democrats in last week’s New York primaries.

Her supporters say volunteers from around the country completed hundreds of thousands of calls over the weekend before the primary, urging Denver voters to return their ballots.

DeGette, for her part, notes that she’s poised to take the gavel of an important subcommittee on public health policy in the next Congress, if Democrats win the majority in the House, as polling suggests is likely.