State Rep. Summer Lee speaks to supporters before being endorsed by Sen. Bernie Sanders during a campaign stop in Pittsburgh, on May 12, 2022.
CNN  — 

Pennsylvania state Rep. Summer Lee will win the fiercely contested Democratic primary for the 12th Congressional District, CNN projected Thursday, overcoming an onslaught of outside money to narrowly defeat her moderate rival, attorney Steve Irwin.

As of Thursday morning, with nearly all of the votes counted, Lee’s lead over Irwin was less than a percentage point.

The Pittsburgh-area race to succeed retiring Democratic Rep. Mike Doyle, who had endorsed Irwin, has been one of the most expensive House primaries in the country so far. A pair of pro-Israel groups spent more than $3 million opposing Lee, who is vying to become to the first Black woman elected to Congress from Pennsylvania.

Lee, a labor and Democratic Party organizer before she first ran for office in 2018, has defied the odds before. She unseated a longtime incumbent to win her statehouse seat in 2018 and was recruited by the progressive group Justice Democrats to run for the seat Doyle is vacating. Lee was bolstered by Justice Democrats and the Working Families Party, but her allies – which spent about $1.4 million on her behalf – were outstripped by the American Israel Public Affairs Committee’s new super PAC, United Democracy Project, and Democratic Majority for Israel.

But in the end, Lee, who was endorsed by a variety of local groups, Pittsburgh Mayor Ed Gainey and progressive leaders such as Vermont Sen. Bernie Sanders, secured a narrow victory.

“They hit us with everything they had, we clawed and we ran, and we got the power of the people,” Lee said on election night earlier this month. “We’re out here in Western Pennsylvania fighting for the future of the whole country.”

Her success delivers a hit of adrenaline to the progressive movement, which saw two of its allies lose open-seat races in North Carolina after facing a similar surge in outside spending.

In Pittsburgh, though, the backlash to the attacks on Lee was especially heated. In an interview days before the primary, Lee called the volume of spending against her “obscene” and said it was intended “to send a very specific message: not just that we’re trying to win an election, but we’re trying to destroy you, we’re trying to depress voter turnout and we’re trying to discourage voters.”

Attacks paid for by outside groups targeting Lee’s alleged disloyalty to the Democratic Party prompted a joint reply from local officials, including Gainey, who sent an open letter to Irwin’s campaign urging him to condemn the attacks.

“As Democrats from across the commonwealth, we find it shameful that you would team up with a corporate super PAC that has endorsed over 100+ pro-insurrectionist Republicans to attack and smear our Democratic colleague, state Rep. Summer Lee, as not a Democrat,” the Lee supporters wrote.

Irwin’s campaign defended the content of the ads and the group making them, with a spokesman telling the Pittsburgh Tribune-Review at the time that “Irwin is proud to stand up for the Jewish state of Israel and America’s strongest ally in the Middle East.”

On election night, with Lee leading and her allies confident she would prevail, Justice Democrats executive director Alexandra Rojas took a victory lap.

“This is a resounding defeat against Republican-funded Super PACs and the corporate-friendly establishment,” she said in a statement. “Democratic voters don’t want to be sold corporate millionaire candidates, they want working-class progressive leaders that will build a people-powered movement for everybody.”

Top officials from the groups that spent the most to defeat Lee, United Democracy Project and Democratic Majority for Israel, said their efforts had been successful in keeping the race close and pointed to Lee’s standing in the district before they got involved in the race as the decisive factor.

“Summer Lee is an exceptional candidate and was already an elected official who generated millions of dollars from super PACs and individuals,” DMFI PAC president Mark Mellman told CNN. “Her losing what EMILY’s List’s pollster called a ‘commanding’ 25-point lead, sends a message about her politics that is perhaps more salient than her long predicte