A six-way Democratic primary for a Pennsylvania congressional district is about to become a battle of the super PACs, with a mysterious “centrist” organization attacking two of the candidates and billionaire Tom Steyer going in to beat a third.

NextGen America, founded and largely funded by Steyer, announced Thursday evening that it would spend at least $100,000 on advertising in Pennsylvania’s 7th Congressional District. The target: John Morganelli, a longtime district attorney who gained local notoriety for using state law to cut off services to undocumented immigrants.

“In 2018, there is no room in the Democratic Party for a man who denies a woman her right to choose and who engages in hateful and dishonest dialogue about immigrant communities,” Steyer​ said in a statement. “If we want to win in 2018 and beyond, we need our own bold, optimistic, and progressive vision for the future. Democrats deserve better than John Morganelli.”

Morganelli’s immigration stance, which has long put him at odds with his party, has been a heated topic in the primary. In a 2014 speech to a local tea party group, Morganelli bemoaned how “the Democratic Party, that I’ve been a member of since I could vote, has become the de facto party for illegal immigration.” After the 2016 election, Morganelli tweeted at President-elect Trump to suggest himself for an appointment, and noted that he’d worked with Kansas Secretary of State Kris Kobach, then considered to be a candidate to run the Department Homeland Security.

“I testified in Washington years ago against the DREAM Act, and against all kinds of legislation that benefits illegals,” Morganelli said in 2014, adding that then-President Barack Obama was “entirely to blame” for that year’s rise in illegal border crossings by Central Americans.

Morganelli has softened the way he talks about immigration, and deleted the Trump tweets after they drew media attention. In direct mail to Democrats, Morganelli’s campaign says that he “hoped for the best” from Trump but came to believe that “he must be stopped.”

NextGen’s move into the race came after the group sponsored a candidate forum, where he said that local law enforcement should work with federal immigration officials — an increasingly toxic position inside his party.

But Pennsylvania Democrats have grown increasingly nervous about the potential for a Morganelli upset, after United Together, an affiliate of the centrist organization No Labels, began spending against his top rivals. Morganelli has slightly trailed both Greg Edwards, a liberal pastor, and Susan Wild, an Allentown city solicitor, in fundraising. Sen. Bernie Sanders (I-Vt.) has endorsed Edwards and will campaign for him Saturday, while Emily’s List has endorsed Wild, and is on the air with a TV ad publicizing Morganelli’s immigration stances, tying him to Trump.

Starting last week, however, supporters of both Edwards and Wild reported receiving direct mail attacking their candidacies, paid for by United Together. In one mailer, the PAC attacked Edwards for paying family members with proceeds from a charity.

In another mailer, the PAC attacked Wild for allegedly failing to act when Allentown’s mayor was embroiled in scandal.

According to United Together’s latest Federal Election Commission filings, it has spent $37,408 so far on the negative mailers. But little else is known about the PAC. It first filed with the FEC in March 2017, and it had raised $810,633.29 by the time it began intervening in Pennsylvania. More than half of that money came from just two donors: White Sox and Bulls Chairman Jerry Reinsdorf ($300,000), and former Major League Baseball commissioner Allan “Bud” Selig ($125,000).

The PAC’s ties to No Labels were first reported in March by Chicago Sun-Times reporter Lynn Sweet, after other PACs founded by No Labels donors intervened to stop Marie Newman, a Democrat challenging Rep. Daniel Lipinski (D-Ill.) in Illinois’ 3rd Congressional District.

But while No Labels has discussed the work of its affiliate PACs in Illinois, it has said nothing about Pennsylvania. Media requests sent Thursday were not answered; the group’s political director expressed a willingness to talk, but did not respond when asked about the Pennsylvania race.

United Together also has been opaque about its ideology and intentions. Its website contains no contact information and only a generic statement saying that the PAC “supports bold progressive leadership in government.” Its first FEC filings included a generic email address; an email sent there Thursday went unanswered.

“We know that this is a conservative PAC that believes it can sway voters through skewed information,” Edwards said. “It’s to be expected. Obviously, they’re threatened by our campaign and our candidacy. It’s just interesting that they targeted the only true progressive candidate running.”