MIAMI — New York City mayor and 2020 Democratic presidential candidate traveled to Miami for Wednesday’s Democratic debate, and some of his fellow New Yorkers tagged along for the ride, but they weren’t well-wishers.

While de Blasio touted his executive experience onstage, including running the nation’s largest police department, the Police Benevolent Association (PBA), a powerful union of rank-and-file New York Police Department (NYPD) officers, announced they would be protesting outside the debate venue. The PBA also bought a digital ad displayed on a truck, as well as a full-page ad in The Miami Herald declaring that de Blasio “puts WORKING PEOPLE LAST.”

“He has devoted far more time to chasing his own political ambitions than to addressing New York City’s myriad crises—the population of homeless New Yorkers is ballooning and the mental healthcare system is in shambles, all of which has only added to the challenges police officers face on the streets,” PBA president Pat Lynch said in a statement.

It was just the latest in the long-running and bitter relations between the PBA and de Blasio. In 2014, as New York City simmered with tension following the August 2014 death of Eric Garner at the hands of an NYPD officer, de Blasio told the story of giving his biracial son “the talk” about how to deal with police. For de Blasio, it was intended to be a heartfelt plea for unity, but for the PBA and many in the NYPD who already distrusted the mayor, it was a betrayal of the rankest kind.

Several months later, two NYPD officers were murdered, and Lynch exacted his revenge. “There’s blood on many hands tonight,” Lynch declared. “That blood on the hands starts at City Hall in the office of the mayor.”

When de Blasio attended the two officers’ funerals, many NYPD officers infamously turned their backs on him.

However, de Blasio brought the story up again on the debate stage Wednesday. “Something that sets me apart from all my colleagues running in this race and that is for the last 21 years I’ve been raising a black son in America,” de Blasio said. “I have had to have very, very serious talks with my son…including how to deal with the fact that he has to take special caution.”

“We need to have a different conversation in this country about guns, but also a different conversation about policing,” he continued.

In the spin room following the debate, de Blasio’s senior campaign advisor Steve Jarding dismissed the PBA’s protests.

“Crime’s down in New York,” Jarding says. “If you want to talk about his record, that’s one of the most powerful parts of it. New York has done a lot of good things on his watch. Yeah, not everyone’s going to be happy about it, but at the end of the day. He’s done retraining of police, he’s ended stop-and-frisk. [Stop-and-frisk] disproportionately hurt people of color, particularly young black men. He stopped it, and crime didn’t go up; it went down. That’s what police want, and I think most police officers would say, ‘He’s been good by us.'”

Whether or not that’s true, the PBA intends to spend its money and its energy dogging de Blasio for the rest of his campaign.