One of the mayor's allies is now suing him over his controversial budget cuts.

District Council 37, the city’s largest union of municipal workers, is suing Mayor Eric Adams and a handful of city agencies over the elimination of a critical job training program that employs 3,000 sanitation workers and park employees.

In a statement, the head of the union, Henry Garrido, called the cuts “reactionary budget reductions” and accused the city of using union workers as “scapegoats for the crisis.”

“New Yorkers are already suffering from the gaps in service caused by the 20,000-plus vacancies that existed before the latest round of [Program to Eliminate the Gap] cuts. Replacing these [Job Training Participant Program] workers with contracts is not only costly and short-sighted, it’s an illegal disservice to the working class people who occupy those jobs,” read a Wednesday statement from Garrido.

The lawsuit specifically points to the cutting of the Park Opportunity Program, a job training program for New Yorkers on public benefits, which helps struggling New Yorkers.

The lawsuit comes just two days after Garrido testified against the cuts at a City Council hearing on Monday.

“Some of the worst things we’ve seen in this budget process has been that they are looking to cut the job training participants not by 5%, not by 15%, but by 100%,” Garrido said.

Garrido added that the cuts undermine the final budget passed by the mayor and City Council back in June.

“It really makes a mockery of the process that we have of the counterbalances of government in the city of New York where the City Council and the mayor negotiate a budget collectively,” Garrido said while admonishing Adams for making cuts months after City Council and the administration shook hands on a final budget.

“I will say this, it goes into the category of broken promises,” Garrido added.

City Hall, in a statement, pointed to the $7 billion budget gap facing the city due to several factors, including the influx of migrants arriving in the city. It also noted the contract deal struck between City Hall and the union in Feburary.

“We are confident that we took all appropriate steps in preparing the November plan, and we will review the complaint,” read the statement from Liz Garcia, the mayor's deputy press secretary.

The lawsuit undermines Adams' long-standing history of union support.

“The lawsuit is a provocative move and it is a clear statement of where the politics is moving in this city, and the mayor has to be concerned about that,” said Tyrone Stevens, a Democratic strategist.

The lawsuit raises further questions about the administration’s ability to manage their finances.

“Now the city appears to be choosing to go toward more expensive contractors in the midst of a budget crisis, so there’s going to be a question obviously of whether we have a budget crisis or budget management crisis,” Stevens said.

Some of the city workers District Council 37 represents are social service workers, 911 operators, school crossing guards, food service workers, park workers and library employees.

The next round of budget cuts are set for January.