Progressive Democrats are claiming victory in 3 key House primaries and the establishment's knives are out

• Progressive Democrats had a good night in Tuesday's primaries after losses earlier this year.
• Progressives are poised to win three important House primaries in Oregon and Pennsylvania.

Progressive Democrats caught a much-needed break on Tuesday night, after coming up short in an earlier spate of elections this cycle.

The progressive left is claiming victory in three key House races in Oregon and Pennsylvania, though votes are still being tallied. Should their candidates prevail, it would give them momentum heading into a busy summer of primary elections, in which Democrats from across the party's ideological spectrum are fighting to ensure their side has the upper hand.

The Democrats that surged ahead on Tuesday night "were unashamed in defining that they are progressive," said Kristal Knight, a Democratic strategist who's worked with candidates and political groups across the party's spectrum. "That has been something that has won many voters over, saying, 'This is where I stand, this is what I believe in, and this is the kind of Democrat I am.'"

In Pennsylvania, state Rep. Summer Lee appears poised to defeat her more centrist opponent, Steve Irwin, to win the Democratic nomination for a seat representing the Pittsburgh area. The race has not yet been called, but Lee leads Irwin by 47% to 41% as of Wednesday morning. Progressives also celebrated John Fetterman's victory in the Pennsylvania Senate primary, though the candidate has tried to eschew labels like "progressive" or "centrist" on the trail.

Meanwhile in Oregon's 5th district, incumbent Rep. Kurt Schrader, a member of the centrist Blue Dog Democrats in Congress, trails progressive challenger Jamie McLeod-Skinner by about 20 percentage points.

McLeod-Skinner ran a campaign that painted Schrader, a 13-year veteran of the House, as an out-of-touch establishment figure who had held up key parts of the Democrats' agenda. She won despite an infusion of support for Schrader from the Democratic Congressional Campaign Committee and President Joe Biden himself.

Over in Oregon's 6th district, Decision Desk HQ and Insider are projecting state Rep. Andrea Salinas will win against well-funded political novice Carrick Flynn, who'd benefitted from the largesse of a cryptocurrency billionaire.

Flynn also won support from the Democrats' House Majority PAC, effectively anointing him the establishment's preferred candidate. Meanwhile, Salinas had the support of Massachusetts Sen. Elizabeth Warren, one of the standard bearers of the progressive movement.

"I saw the power last night," said Oregon Sen. Ron Wyden, who won his primary on Tuesday. "Voters said you better go out there and take on the special interests."

"Democratic voters sent a clear message last night: we're done with putting people in Congress who sabotage our whole agenda," said progressive organizer Kai Newkirk, who singled out Democratic Sens. Joe Manchin and Kyrsten Sinema for their votes against Biden's agenda items.

"Democrats want our representatives to at least be actual Democrats," Newkirk continued. "And the strong progressive credentials of Summer Lee, Fetterman, and McLeod-Skinner show there is real hunger among most Democrats for representatives who will fight to actually get big things done that make a real difference on the huge issues facing our democracy, our planet, and working class people."

But taken as a whole Tuesday night's primaries revealed a much deeper fissure within the Democratic Party.

Earlier in May, incumbent Rep. Shontel Brown defeated former Bernie Sanders advisor Nina Turner for the second time in what had been billed as a showdown between centrist and progressive Democrats.

Moderate Democrats succeeded in House races in Kentucky and North Carolina on Tuesday. And not everyone was thrilled at progressives' gains this week.

"It's just a shame, it really is," Manchin, a conservative West Virginia Democrat, told CNN of Schrader's loss. "Kurt is a good man. A really good man."

"It's a really sad scenario when you lose people that are willing to work, to find solutions and not just retreat back to their corners," Manchin continued. "And that's why people are losing confidence in us being able to solve problems here in Congress."

The progressives who performed well in Tuesday's primaries had to contend with millions of PAC dollars spent against them — and in support of Democratic candidates who identified as more centrist.

Sen. Bernie Sanders, who endorsed Lee in Pennsylvania, praised her campaign and railed against the sheer amount of outside money that was spent to try to derail her.

One PAC, the United Democracy Project, spent nearly $2 million to attack Lee and bolster Irwin in the final weeks of the race, the Washington Post reported.

"Summer ran a brilliant campaign, a really strong campaign," Sanders told reporters at the Capitol. "I think without that super PAC money she probably would have won by 20 points. It was just a huge flood of money."

Oregon's 6th district became a textbook case of excessive political spending. It was the third most expensive House primary in the country to date, thanks to nearly $11 million in donations to Flynn that POLITICO traced back to cryptocurrency CEO Sam Bankman-Fried.

"What we know for certain is, there is infighting within the party," Knight told Insider. She did not see the party settling the issue anytime soon, but rather predicted the debate would continue to play out at the ballot box all year.

"Even in other races that will continue to pop up over the summer, these will be the defining questions for the Democrats," Knight continued. "Which side do you want to be on? Which side is going to be able to beat a Republican in November? And which side is going to vote with the President's agenda?"