The upset defeat of a former Democratic congressman in a Nebraska House primary has become the latest sign of an ascendant left within the Democratic Party.

Social worker and nonprofit executive Kara Eastman’s defeat of former Rep. Brad Ashford John (Brad) Bradley AshfordThe Hill's Morning Report - Presented by Facebook - First lady casts Trump as fighter for the 'forgotten' House Democrats target Midwestern GOP seats Tight race brewing in Nebraska House contest: internal poll MORE in Tuesday’s primary for the House seat Ashford once held is the latest shot of adrenaline for the left, which also saw victories by a number of left-of-center candidates in Pennsylvania’s primaries.

ADVERTISEMENT

Progressives see Eastman’s win as mounting evidence that candidates backing “Medicare for all” and other policies from the party’s left wing can win over voters, as moderates and progressives battle for the soul of the party.

But Washington Democrats are worried the surging left could end up costing the party seats in more centrist districts this fall — including the one that Eastman will now try to win back for her party. President Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE won the Omaha-based seat by 2 points in 2016, which now-GOP Rep. Don Bacon won by a similar margin.

“The only thing many national observers know about Eastman is that she beat a Blue Dog-endorsed former congressman while running to the left, so it's pretty easy to caricature her as something like a progressive version of a tea partier. But like most caricatures, it would be inaccurate,” Daily Kos elections writer Jeff Singer wrote after Eastman’s win, adding that her support for progressive policies “are about where the Democratic base is now, and these policies tend to poll well with the larger public, too.”

During the primary campaign, Eastman highlighted the fact that she was the only candidate in the race backing single-payer health care. She also supports a higher minimum wage, an assault weapons ban and free tuition to state universities and colleges for families who earn less than $125,000 a year.

Eastman also focused a large part of her campaign on challenging the status quo, saying in a TV ad that she’s “tired of hearing that Democrats don’t have a backbone, that we don’t stand for anything.” Ashford’s defeat makes him the latest in a string of current and former lawmakers to lose primaries around the county amid voters’ frustration with Washington and Congress.

While progressives were in Eastman’s corner, the Democratic Congressional Campaign Committee (DCCC) elevated Ashford to its “Red to Blue” program, which highlights top candidates and provides financial and organizational support. Ashford was also backed by the centrist Blue Dog Coalition, which he belonged to in the House before losing the seat in 2016.

With the Red to Blue designation, the DCCC and party leaders have signaled that they believe candidates with moderate backgrounds are more poised for victory in the general.

In an interview with The Hill, Eastman pushed back on the narrative that a progressive candidate won’t fare well in November, arguing that her campaign helped get out voters.

“We continue to run conservative Democrats and they lose, so what we found in this campaign is so much enthusiasm, so much support that we really ignited the base,” Eastman said.

“One issue in the district is turnout, and part of that is we haven’t run a real progressive Democrat and I think this message is strong and will continue out through the general election.”

Eastman said that progressive icon Sen. Bernie Sanders Bernie SandersButtigieg stands in as Pence for Harris's debate practice Bernie Sanders warns of 'nightmare scenario' if Trump refuses election results Harris joins women's voter mobilization event also featuring Pelosi, Gloria Steinem, Jane Fonda MORE (I-Vt.) called her the following morning to congratulate her, saying, she recalled, “I heard you upset the Democratic establishment.”

National Democrats appeared to rally behind Eastman after her win. DCCC spokesman Evan Lukaske released a statement highlighting Eastman’s record running a nonprofit and deep ties to the district, saying, "These primary results show Kara is running strong and she is well positioned to win this fall."

But some Democrats remain fearful that she’ll have a tough time overcoming a Republican incumbent in the fall.

Eastman’s victory prompted some election handicappers to move the race toward the Republican. Sabato’s Crystal Ball at the University of Virginia shifted the race from "toss-up" to "lean Republican," while noting that the Democrat still has a shot in November.

Still, others are downplaying the notion that Eastman will be a weaker general election candidate. While they acknowledge her liberal stances will be fodder for Republican attacks, they argue that Eastman can effectively put enough distance between herself and the nation's capital.

“The verdict is still out whether our prospects in this district got better or worse because of the primary,” said Jesse Ferguson, a former top aide to the DCCC. “We got a more progressive candidate who is less tied to the problems of Washington. The benefit from that could outweigh any downsides.”

“It may be harder for her to insulate herself from [Republican] attacks, but it also will be far easier for her to run against the status quo in Washington.”

While some are fretting that Eastman’s ideology will hurt Democratic chances for the seat, some Democrats argue that Eastman’s less-than-impressive fundraising could be even more of a liability in running against an incumbent lawmaker.

During the primary, Eastman raised $356,000, with Ashford outpacing her by more than $200,000.

With no opponent in the Republican primary, Bacon raised nearly $1.5 million, and has $830,000 cash on hand. That’s a huge cash advantage over Eastman, who enters the general with just $71,000 in the bank.

Meanwhile, Republicans are reveling in Eastman’s victory, saying it improves their chances in the general election.

The National Republican Congressional Committee conducted polling that shows Bacon in much better shape in a general election match-up against Eastman than Ashford. The group’s internals show Bacon ahead by 10 points over Eastman — compared to just a 2-point advantage over Ashford in a hypothetical matchup.

“Ultra-progressive Kara Eastman’s political views are more aligned with Californians, not Nebraskans,” said Michael Byerly, a spokesman with the GOP super PAC, Congressional Leadership Fund. “CLF looks forward to informing voters about her stances on universal health care, raising taxes, national security, and a lot more as the year progresses.”

It remains to be seen how heavily groups will prioritize this race, but super PACs on both sides of the aisle have already reserved airtime in Omaha.

Prior to the primary, the Congressional Leadership Fund reserved $1.6 million on TV and digital, while House Majority PAC, a super PAC with ties to Democratic leadership, booked $896,250 in ads for broadcast and cable.

Nebraska wasn’t the only state where progressives had a great night.

In Pennsylvania, a number of wins on the federal, statewide and local levels powered what became a triumphant night for progressives.

In one House race, Democrat Rachel Reddick, a former Republican who ran as a centrist, lost to Scott Wallace, a progressive who poured in $2.5 million of his own money and will now face GOP Rep. Brian Fitzpatrick Brian K. FitzpatrickFlorida Democrat introduces bill to recognize Puerto Rico statehood referendum DCCC reserves new ad buys in competitive districts, adds new members to 'Red to Blue' program 2020 Global Tiger Day comes with good news, but Congress still has work to do MORE in another tough swing seat.

District Attorney John Morganelli, who drew vehement opposition from progressives over his hard-line immigration views and anti-abortion views, lost a House primary to Allentown City Solicitor Susan Wild, who was backed by EMILY’s List. She’s running for the seat once held by ex-GOP Rep. Charlie Dent Charles (Charlie) Wieder DentRepublican former Michigan governor says he's voting for Biden Biden picks up endorsements from nearly 100 Republicans Bush endorsing Biden? Don't hold your breath MORE, which would have been narrowly carried by 2016 Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonButtigieg stands in as Pence for Harris's debate practice Senate GOP sees early Supreme Court vote as political booster shot Poll: 51 percent of voters want to abolish the electoral college MORE under Pennsylvania’s new congressional map.

Braddock Mayor John Fetterman, who was backed by Sanders and had a surprisingly strong showing in Pennsylvania’s 2016 Democratic Senate primary, defeated the incumbent for lieutenant governor.

And in legislative seats in Pennsylvania, four Democratic candidates backed by the Democratic Socialists of America won primaries.

Those wins, and others like them, could reverberate beyond November. If the party’s progressive wing gains more ground in primary fights, potential 2020 White House contenders could also try more to court the Democratic left.

But while progressives are celebrating their primary victories, Democratic strategists say the real work begins now. Some argue that national progressive groups who got their candidates over the primary finish line will need to continue backing them ahead of November.

They say that if progressive groups don’t arm candidates with enough resources and staffers to prevail in the general, they could suffer general election defeats that could undermine their mission and cost Democrats their chance at the House majority.

“If you want to prove that Democrats can and should run on a more progressive agenda, they now have to deliver a victory in November for the more progressive candidate or else they’ve proven everyone’s worst fears,” said a Democratic strategist.