One of the most conservative Democrats in Congress may lose his primary on Tuesday.

Rep. Dan Lipinski (D-IL) spent much of his career antagonizing his own party as an outspoken pro-life advocate who has been hostile to gay rights and has voted against Democratic priorities from the DREAM Act to Obamacare to Planned Parenthood funding. After more than a decade representing a safely Democratic seat stretching from Chicago’s Southwest Side out to largely working-class suburbs, he’s facing the toughest primary challenge of his career from former ad executive Marie Newman, a staunch liberal whose campaign has gotten a major boost from a constellation of national progressive groups seeking his ouster.

Democrats who have closely monitored the election say it could go either way, but that she has the momentum in a year where the liberal base is furious and activated and being a centrist in a safely Democratic district isn’t exactly a selling point.

“Dan Lipinski has walked away from the Democratic values that we all hold dear, particularly that relate to women and women’s health care. This is not the time for someone who’s going to champion anti-women’s positions and anti-LGBTQ positions,” EMILY’s List President Stephanie Schriock told TPM during a Thursday conference call. “We think she’s going to pull this out on Tuesday.”

Besides the pro-choice EMILY’s List and NARAL Pro-Choice America, Newman also has support from the pro-LGBTQ Human Rights Campaign and the Service Employees International Union. The groups have spent more than $1 million to back her campaign. She also has endorsements from Sens. Kirsten Gillibrand (D-NY) and Bernie Sanders (I-VT), as well as Reps. Luis Gutierrez (D-IL) and Jan Schakowsky (D-IL), who has dispatched a top staffer to aid Newman’s campaign. Some top local Democrats, like Cook County Board President Toni Preckwinkle (D), have gotten on board as well.

Lipinski, allies say, was caught a bit flat-footed by the challenge. He told TPM a few weeks ago that he wasn’t sure “why anyone believes this is going to be a close race to begin with.” He was slow to launch TV ads slamming Newman, allowing her and her allies weeks to themselves to define the race. That allowed Newman to raise her once-nonexistent name ID and drill him for his regular breaks with his party, not an easy feat in Chicago’s expensive media market especially since it’s been saturated with heavy campaign spending from the billionaires running for Illinois governor.

A Lipinski poll taken early in the race found him with a 30-point lead; a recent survey from NARAL found Newman within two points.

“I don’t think he realized what a fight he’d be in, and the dynamic didn’t change until the SEIU and progressive groups flipped the switch and started spending,” one Chicago Democratic strategist whose job precludes them from talking on-record told TPM.

But those following the race say not to count Lipinski out just yet. He has close ties with Chicago’s still-powerful Democratic machine and its head, state party chairman and state House Speaker Mike Madigan (D). The well-organized building trade unions are firmly behind him as well, after a decades-long relationship with him and his father, former Rep. Bill Lipinski (D-IL), who installed his son in his old seat when he retired in 2004. Lipinski and Madigan made sure the current incarnation of the district had as many blue-collar white ethnic Democrats as possible in the last round of redistricting in an effort to boost his standing.

There’s no love lost between the Lipinski and Newman. Lipinski, a co-chairman of the fiscally moderate Democratic Blue Dog Coalition, regularly dismisses Newman as part of the “Tea Party of the left” in interviews, while Newman attacked him as a “full-on Republican” who is “anti-immigrant” and “on a mission against women” in a Thursday conference call with EMILY’s List.

The winner of the Democratic primary will be a lock in the general election — Hillary Clinton carried the district by 15 points and Republicans are set to nominate an actual neo-Nazi that party leaders have disavowed after failing to recruit a real candidate.

Lipinski has gotten his own cavalry in the race. The centrist group No Labels has spent close to $1 million on TV and mail pieces through a number of new super-PACs largely financed by Chicago Bulls and White Sox owner Jerry Reinsdorf, an old friend of Lipinski’s father.

The group has been hammering Newman for going into business with a felon – she and her husband briefly partnered with an ex-con in a restaurant venture before disengaging months later.

But one of its attacks may end up backfiring on Lipinski. The group sent a mailer contrasting Newman to President Obama, saying he was “known for leading” while she was “known for misleading.” That incensed some of Obama’s top deputies, who were quick to point out that Lipinski not only voted against Obamacare, he publicly refused to endorse Obama in his 2012 reelection campaign. Former top Obama adviser David Axelrod lit into him on Twitter, then held a press conference with former advisers to attack Lipinski as a hypocrite.

In fact, Lipinski was one of the few Democrats who voted against the Affordable Care Act, which makes the Obama mailer even more galling. — David Axelrod (@davidaxelrod) March 14, 2018

He also got a last-minute boost from the anti-abortion Susan B. Anthony List, which is spending a small amount and sending canvassers to knock on 17,000 doors to turn out the district’s pro-life (largely Catholic) voters.

“Dan Lipinski is one of the few remaining pro-life Democrats in Congress, and he has shown extraordinary courage,” SBA List President Marjorie Dannenfelser said in a Thursday statement. “He stood firm against Obamacare’s expansion of taxpayer-funded abortion under intense pressure from party leaders to give in. Now Lipinski is under attack for his pro-life convictions again, with a primary challenger backed by the radical abortion lobby. That’s why SBA List is going all in for Lipinski.”

Lipinski’s campaign didn’t respond to multiple calls and emails to discuss the race.

Lipinski’s side has had the edge in recent spending and, though the SEIU is all-in for Newman with its ground game, his field operation has proven formidable in the past.

“It’s going to be tough, but I think he’s going to win,” said one Lipinski ally who’s helped on the race.

But others aren’t so sure, arguing her message has been a much more potent one in the current political climate.

“Her messaging on choice and gay rights is a lot stronger than his attacks on her business and working with felons,” said the Chicago-based Democratic strategist. “It’s looking like a coin flip here.”