PHILADELPHIA — In the most-watched race for Congress in Philadelphia in more than a decade, State Rep. Chris Rabb has cast himself as the unabashed anti-establishment leftist. He's refusing donations from corporations, calls the war in Gaza a genocide, and wants to abolish U.S. Immigration and Customs Enforcement.

But despite announcing his campaign more than six months ago, he had yet to amass support from much of the city's progressive flank, leading observers to wonder if he would be able to tap into the movement's network of donors and volunteers.

It appears they're coming around.

Rabb this week has won an endorsement from One PA, a progressive political group that's aligned with labor and most of the city's left-leaning elected officials. That comes after the environmental justice group Sunrise Movement said it, too, would back Rabb.

"This is a moment when democracy is at stake," said Steve Paul, One PA's executive director. "If there was any moment for the style of leadership that Chris [Rabb] brings to the table, it's this moment."

Rabb said he's "energized" by the endorsement and what it means for the campaign.

"Our movement is growing every single day," he said.

The questions now are whether some of the city's most prominent progressive elected officials will lend their endorsements to Rabb, and if deep-pocketed national organizations will spend money to back him.

For example, Justice Democrats, a progressive political action committee, said it's "very closely looking at this district." And the Working Families Party, the labor-aligned third party that supports progressives across the nation, has endorsed candidates in four other congressional races with competitive primaries — but not yet in Philadelphia's. The group previously spent millions to boost candidates in the region.

Rabb, who hails from the voter-rich Northwest Philadelphia, is one of several likely front-runners seeking the Democratic nomination to represent the 3rd Congressional District, which encompasses about half of Philadelphia. U.S. Rep. Dwight Evans is retiring after holding the seat since 2016.

Progressives and democratic socialists — energized by Mayor Zohran Mamdani's win last year in New York City — see a major opportunity to install one of their own in the district, which is the most Democratic in the nation.

The primary election — the marquee race in deep-blue Philadelphia — isn't until May. But some on the left say the movement should have already coalesced around Rabb.

"We will probably regret it in the end, because this is a seat we should win," said one leader of a progressive organization in the city who requested anonymity to speak freely about the political dynamic.

Rabb is seen as something of a lone operator with his own political apparatus. He didn't come up through the newer progressive organizations that have run their own candidates for office in the city. Rather, he won a seat in the state House for the first time a decade ago when he toppled an establishment-backed Democrat.

Some of the city's progressive leaders say they expect to back Rabb but that they were waiting to see how the field shaped up.

Last year, there were efforts to recruit other left-leaning candidates to run, including City Councilmember Kendra Brooks of the Working Families Party, and State Rep. Rick Krajewski, according to three sources with knowledge of the efforts who spoke on condition of anonymity to preserve relationships. Both decided against running.

Brooks — who emerged as a face of the Working Families Party six years ago after she became the first third-party candidate to win a seat on Council in 100 years — is likely to back whomever the organization endorses. The group is still in the midst of its endorsement process.

"We're confident that we will land on a progressive who will fight for working people, not billionaire donors, big corporations, or special interests," WFP spokesperson Nick Gavio said.

Krajewski, who represents parts of West Philadelphia, has also not endorsed a candidate but he said he will. Rabb, according to Krajewski, has the qualities necessary to be a member of Congress during "a pivotal moment for our country."

"The question is: Do we allow the fascists and the ruling class to double down on this insanity that they're pushing? Or do we use this opportunity to agitate and say a different world is possible?" Krajewski said. "That's what I want from my member of Congress. Chris [Rabb] has demonstrated that he's clear about that."

Meanwhile, other candidates in the wide-open Democratic primary have tried to pick off progressive support.

State Sen. Sharif Street, the former chair of the state Democratic Party, is seen as the establishment's pick for the seat. But he also has alliances with some of the city's most progressive leaders.

That includes a decades-long relationship with Councilmember Rue Landau, who often votes with Council's progressive bloc and is the first openly LGBTQ person ever elected to Council. Two sources familiar with Landau's thinking said she is strongly considering endorsing Street.

Street has also worked closely on criminal justice reform matters with District Attorney Larry Krasner, perhaps the city's most prominent elected progressive. He inherited some of Krasner's political staff to manage his campaign.

However, several other candidates in the congressional race could be in the running for backing from Krasner, who recently won his third term in office in landslide fashion. Rabb, Street, and State Rep. Morgan Cephas previously endorsed Krasner for reelection.

The crowded field may also mean that some elected officials choose not to get involved.

State Rep. Tarik Khan, a Democrat and nurse practitioner who has been backed by progressive organizations, said he has relationships with several leading candidates. That includes his colleagues in Harrisburg, as well as Ala Stanford, a surgeon. She and Khan were both prominent vaccine advocates during the COVID-19 pandemic.

"There's a lot of good choices in this race," Khan said. "I'm probably just going to let the process play out."

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