Lefty activists energized by the apparent victory of Alexandria ­Ocasio-Cortez protégé Tiffany Cabán in the Queens DA Democratic race are threatening to set up primary challenges against long-serving Assembly Dems if they don’t pass a slate of progressive laws in the next session.

“All the things that didn’t get done in 2019 that we’re very frustrated about . . . There’s no excuses anymore,” said Mia Pearlman of True Blue NY, one of the grassroots groups that backed challengers to Democratic state legislators who caucused with Republicans in 2018.

“The momentum is only going to grow . . . The Bronx machine should be scared, and all machines or king-makers are going to continue to lose power in this atmosphere,” Pearlman added.

Working Families Party spokesman Bill Lipton predicted a “rising tide of young people and progressive activists” voting in upcoming elections. “I think we made important progress — there’s still a lot more to do,” he said.

The emboldened stance comes less than two days after democratic socialist Cabán declared victory over machine-backed Borough President Melinda Katz in in Tuesday’s primary.

Cabán swept the same western Queens assembly districts where Ocasio-Cortez trounced 10-term Congressman and party boss Joe Crowley in a seismic upset last year.

That could spell trouble ahead for several establishment pols representing those districts, including Assembly members Mike Miller (D–Woodside), Michael DenDekker (D–Jackson Heights) and Cathy ­Nolan (D–Long Island City).

Cabán received a total of 33,814 votes to Katz’s 32,724, but paper ballots have yet to be counted.

Gov. Cuomo, a Katz backer, blamed low turnout for Cabán’s likely victory.

State progressives won a slew of legislative victories this year, after being stymied for nearly a half-century by a Republican-controlled state Senate.

But activists heaped ire on Assembly Speaker Carl Heastie (D-Bronx) — whose political action committee gave Katz $20,000 — and on other veteran Dems for failing to approve leftist pet issues, such as publicly financed elections and the elimination of prison solitary confinement.

“We know who the champions were, we know those who were hiding,” Pearlman said, adding the group “hasn’t chosen our targets yet” but is strategizing.

Local members of Congress are apparently no safer — Rep. Eliot Engel (D–Bronx/Westchester) is fending off two primary challengers from the left.