Mayor Bill de Blasio can’t escape the long arm of the NYPD’s biggest union as he continues his quixotic quest for the White House.

Nearly two dozen members of the city’s Police Benevolent Association plan to protest against Hizzoner before he takes the stage at Wednesday night’s first Democratic presidential primary debate in Miami.

The PBA expects its ranks to be swelled to around 100 by police union members from Miami and West Palm Beach, as well as retired NYPD cops living in the Sunshine State.

The powerful union — which is headed to arbitration with the city over a new contract — took out a full-page, $15,000 ad in Wednesday’s Miami Herald that features a photo of the mayor smirking and the words “NYC Mayor Bill de Blasio puts WORKING PEOPLE LAST.”

It also had an electronic-billboard truck bearing the same image circling the debate site late Wednesday afternoon.

“From labor to mental health to homelessness, Mayor de Blasio’s abysmal record while running New York City should disqualify him from running the country,” PBA president Patrick Lynch said.

“Voters — and de Blasio’s opponents on the debate stage — deserve to know the truth.”

The de Blasio campaign declined to comment, but released a statement in which several New York City unions — including those representing retail, transit and hotel workers — endorsed him as “the most pro-labor Mayor New York City has had in decades.”

De Blasio has been dogged by the PBA since he launched his campaign on ABC’s “Good Morning America” in May, when cops improbably stood shoulder to shoulder with “Black Lives Matter” activists outside the show’s studio in Times Square.

Days later, a retired NYPD cop protested de Blasio’s campaign swing through South Carolina by holding up a PBA poster and an orange foam hand with the word “LIAR” outside a barbecue joint that the mayor visited in Orangeburg.

De Blasio lucked out and randomly scored a spot in the first of two back-to-back debates Wednesday and Thursday.

But because the 20 candidates were assigned their places inside the Adrienne Arsht Center for the Performing Arts based on popularity, de Blasio’s rock-bottom poll numbers will put him at the far left of the stage.

The debates will be carried live at 9 p.m. on NBC, MSNBC and Telemundo, as well as online.

Additional reporting by Nikki Schwab and Stephanie Pagones