A group of traffic enforcement agents running for union leadership posts are suing the city, saying the NYPD barred them from campaigning inside police precincts after they complained about a plan to replace the department-blue uniforms used by some of the agents.

The Manhattan federal court lawsuit was filed by four traffic agents running for Local 1182 posts and blasts the NYPD for blocking their campaigning, which they say “reverses 40 years of prior practice and “is a blatant violation of plaintiffs’ First Amendment rights.”

The Post exclusively reported in March that the union was steamed over the NYPD’s plan to swap out their blue uniforms for green shirts and black pants, which they said would make their job more dangerous. The idea has since been dropped.

Police Commissioner Bill Bratton has since said the uniforms won’t be changed.

A city Law Department spokesman said they would review the allegations.