A former top deputy in Manhattan District Attorney Cy Vance Jr.’s office is joining the crowded race to unseat her ex-boss, THE CITY has learned. 

Diana Florence, who led the office’s Construction Fraud Task Force until leaving in January amid allegations she withheld evidence, is slated to announce her candidacy Monday in front of the Steinway Tower on W. 57th Street.

That’s where two years earlier the DA’s office charged a construction company doing work on one of the tallest buildings in the city with cheating workers out of hundreds of thousands of dollars in wages, she noted. 

“I’m running because I want to fight for people who never thought they’d win,” Florence, 49, told THE CITY. 

Florence, a native New Yorker, is slated to become the seventh challenger to 66-year-old Vance, who was first elected to lead the office in 2009 following the retirement of longtime DA Robert Morgenthau. 

Other Democrats vying for the seat include Alvin Bragg, a former chief deputy state attorney general; Assemblymember Dan Quart (D-Manhattan); civil rights attorney Tahanie Aboushi; public defender Eliza Orlins; former ACLU lawyer Janos Marton; and Tali Farhadian Weinstein, the former general counsel to the Brooklyn district attorney. 

‘Learned From the Best’

Vance — who has been criticized for not bringing up charges following investigations of film producer Harvey Weinstein and Donald Trump Jr. and Ivanka Trump, and for his office’s support for reducing financier Jeffrey Epstein’s sex-offender status to the lowest classification — has not decided whether he’d seek a fourth term in 2021. 

Recent campaign finance records show Vance, once a prolific fundraiser, has pulled in just $2,101 between mid-January and mid-June, a paltry amount compared to the $1.35 million he stockpiled before his 2017 run. 

A spokesperson for Vance’s reelection campaign didn’t comment directly on the candidacy of Florence, whom he appointed attorney-in-charge of the construction task force in 2015.

“He’s focused on continuing to make New York City’s justice system fairer for all New Yorkers, but particularly those who have been historically impacted by our criminal justice system,” said the spokesperson, Anna Durrett.