New York Rep. Dan Goldman could badly lose his re-election bid, a shocking new survey found.

Former city Comptroller Brad Lander leads the incumbent congressman by a yawning 34 points — 57% to 23% — in the upcoming Democratic primary for the 10th House District, according to the Emerson College poll.

“While all age groups break for Lander, his most significant support comes from voters under 40, who break for Lander over Goldman, 73% to 15%,” said Emerson pollster Spencer Kimball.

Mayor Zohran Mamdani — who also made big gains among the city’s younger voters, propelling him to victory in November — is supporting Lander.

Lander previously represented much of the Brooklyn portion of the district — which encompasses Lower Manhattan and brownstone Brooklyn — while serving in the City Council.

Goldman, a Levi Strauss heir and former federal prosecutor who served as lead counsel in the first impeachment proceeding against President Trump, was first elected to Congress in 2022.

His main liability seems to be his record backing Israel in a progressive district where many Democrats have turned against the Jewish state amid fighting in the Middle East. 

The survey of 450 voters taken on May 16-17 has a margin of error of plus or minus 4.6 percentage points.

Two other Democratic primaries for open seats in the 7th and 12th House districts to replace retiring Reps. Nydia Velázquez and Jerry Nadler, respectively, are too close to call, with a large number of voters undecided, the Emerson surveys found.

In the 7th District, encompassing parts of Brooklyn and Queens,  23% of Democrats favored Democratic socialist state Assemblywoman Claire Valdez, who also grabbed her fellow lefty Mamdani’s endorsement.

Brooklyn Borough President Antonio Reynoso — Velazquez’s pick to succeed her — was near even at 21% support. City Councilwoman Julie Won had 13% support, with a large 43% of voters undecided.

More younger voters supported Valdez while more older voters favored Reynoso, who also has the backing of some other leftists and many establishment groups, according to the Emerson poll in that race.

The results, based on interviews of 350 Democrats, are within the poll’s 5.2 percentage-point margin of error.

In the race to replace Nadler in Manhattan’s 12th House District, 22% of Democrats back state Assemblyman Micah Lasher, 20% support Assemblyman Alex Bores, 11% support Kennedy scion Jack Schlossberg, and 10% favor lawyer George Conway.

About one-third of voters were undecided.

The poll in the 12th District interviewed 425 Democrats and has a margin of error of plus or minus 4.8 percentage points.

The primary takes place June 23, with nine days of early voting beginning June 13.

Mamdani is popular among Democratic primary voters in the three congressional districts: 78% of Democratic voters in the 7th District approve of Mamdani, as do 79% in the 10th District and 66% in the 12th District.

The mayor has not endorsed a candidate — at least yet — in the race to succeed Nadler in a district that encompasses the East and West sides of Manhattan with a large Jewish population.

Mamdani campaign strategist Morris Katz is working for Lasher.

The Goldman campaign insisted the Emerson poll was widely off base.

“This poll is not remotely close to an accurate read of this race,” said Goldman spokesman Simone Kanter.

“The data we’ve seen shows a dead heat after messaging. Emerson is assuming an electorate that looks exactly like the once-in-a-generation turnout Mamdani mobilized when he was on the ballot, with approximately 50% higher youth turnout than a traditional midterm electorate,” Kanter said..

The survey gives short shrift to working-class voters in Chinatown, the Lower East Side, Sunset Park, and Borough Park who “overwhelmingly support Dan,” the Goldman representative said.