A rare open House seat in a newly redrawn New York district attracted a dozen candidates for the Democratic primary on Tuesday, but simmering tension and similar agendas have since allied leading progressive hopefuls against the moderate front-runner -- a strategy that some experts predict could backfire on their own electoral chances because of possible vote-splitting.
Following the post-census redistricting process -- and the state courts rejecting initial Democratic maps as unacceptable gerrymandering -- the new 10th Congressional District is a cross-section of neighborhoods across two boroughs, spanning south Manhattan over the East River into Brooklyn's Borough Park, Dumbo and Park Slope and including sizable Asian and Latino communities, Orthodox Jewish neighborhoods and stretches of tony brownstones.
The redrawing drama set off a chain reaction of incumbents shifting seats, hoping not to lose office: The 10th's incumbent, House Judiciary Committee Chairman Jerry Nadler, opted to run in the 12th against longtime ally Rep. Carolyn Maloney.
His departure invited many other candidates, including freshman Rep. Mondaire Jones, who bounced from his current district (the 17th) because fellow incumbent Sean Patrick Maloney -- head of the House Democrats' campaign arm -- moved from his seat, the 18th, drawing the ire of some rank-and-file members of Congress.
It's against that complicated backdrop that Tuesday's Democratic primary in the 10th will play out.
Among the contenders, the biggest emerging differences are less policy-driven than identity-driven, campaign strategists say. The leading candidates are Dan Goldman, a former prosecutor; Rep. Jones; New York City Council Member Carlina Rivera; and state Assemblywoman Yuh-Line Niou. (Former New York City Mayor Bill de Blasio also tossed his hat in the ring as the 13th candidate but later withdrew.)
The field is generally all in agreement on prominent policy issues such as environmental reform, the codification of abortion rights and assault-style weapon bans -- which is why, operatives say, the contest has focused on differences elsewhere.
Front-runner Goldman, who won an influential endorsement from The New York Times' editorial board, is the wealthiest and most moderate and has the least amount of experience in elected office.
He most prominently served as counsel to House Democrats during then-President Donald Trump's first impeachment trial, in 2019 -- and has cited that work to describe himself as "the only candidate in the race who has been in the trenches standing up to Trump," he told ABC News.
Goldman is no stranger to the district's well-heeled enclaves, which serve as home to celebrities, millionaire mega-donors and influential political pollsters. A Levi Strauss heir, he invested some $4 million of his own money into broadcast ads and cable spots, outspending every other candidate in the race.
The more progressive hopefuls have targeted that wealth, arguing that Goldman's millionaire status estranges him from an economically and racially diverse electorate.
Local strategist Hank Sheinkopf told ABC News that the progressive alliance was the "only strategy," given Goldman's stature in the race so far.
"By joining forces, [progressives] can hope different voter demographics will respond individually," Sheinkopf said. "Gay people will side with Jones, and the Latino vote that might have gone to Goldman can go to Rivera. It's the only strategy they have to try to break apart the coalition Goldman assembled based on his anti-Trump record."
Council Member Rivera told The New York Daily News that Goldman was a "one-note Daddy Warbucks." Rep. Jones and Assemblywoman Niou also joined forces in a joint news conference on Aug. 15, telling supporters -- whose signs read "Anyone But Goldman" -- that "Dan Goldman cannot buy the city of New York."
They contended he is a "conservative" who opposes an expansion of the Supreme Court and holds an unclear position on Medicare for All, two policies supported by the party's left flank.
Goldman has shrugged off his opponents' comments, explaining that they "have different approaches for our shared goals."
"I don't oppose 'Medicare for All,' but I think we are much more likely to help people by reforming the current system," he told ABC News. "As for the Supreme Court, I support term limits, a judicial code of ethics and an investigative body that can look into whether Supreme Court justices lied under oath before the Senate. Adding more justices is just anti-democratic."
Goldman's opponents in the primary have also seized on an unlikely "endorsement" he received -- from Trump himself, via a statement on Trump's social media platform.
Goldman quickly rejected the former president's backhanded comment: "Trump fears me because of my work to successfully impeach him after his Ukraine call, and fears the possibility that I enter Congress."
When asked about the progressive backlash, Goldman told ABC News: "Any candidate who takes his remarks toward me at face value is not fit to represent Congress."
A temporary collective front against Goldman, political experts say, has challenges of its own. Jones, Rivera and Niou have divided endorsements among themselves, just as they may divide up voters. Rivera is backed by New York Rep. Nydia Velázquez and 11199SEIU, a prominent health care union; while Jones has the support of the Congressional Progressive Caucus, New Jersey Sen. Cory Booker and House Speaker Nancy Pelosi.
Niou earned the approval of the Working Families Party, the environmental group Sunrise Movement and the Jewish Vote, a local organization.
"There's nothing wrong with the team-up if this were a ranked-choice election. The issue is that it's not," said Chris Coffey, CEO of Tusk Strategies. "If some progressives drop out and endorse a non-Goldman front-runner, one might defeat Goldman. But it's possible that the progressives together get 50% of the vote, but Goldman ultimately wins with, say, only 28% of the vote because voters are already stretched thin."
(Coffey, though not affiliated with any candidate, has donated to Rivera's campaigns and that of another candidate, state Assemblywoman Jo Anne Simon.)
The progressive candidates in the 10th have, of course, campaigned beyond criticizing Goldman. Jones, Niou and Rivera have all tapped into their experience as elected officials.
Niou told ABC News that her identity as a woman of color with autism motivates her to center her candidacy on disability and reproductive rights.
"It goes beyond Roe [v. Wade] for disabled folks in New York," she said, referring to the reversal of the Supreme Court's decision guaranteeing abortion access. "I support universal health care. We can help low-income mothers of color get formula for disabled babies who can't latch, or gender-affirming help to folks who want to transition but struggle with medication. Every issue is a disability issue."
Tuesday, though, may test whether Democratic voters in the area have only one thing at the top of their minds.
"Trump dominated the discussion yet again. If Goldman wins, it will be because of one reason," said Sheinkopf, the strategist. "And that's because he is the best-known man among Brooklyn elites who hates Donald Trump."