Mayor Bill de Blasio has four more years in City Hall. But with Corey Johnson as City Council speaker, his relationship with the other side of the building is poised to undergo some potentially dramatic shifts.

The pair appeared together at police headquarters Friday to celebrate a major milestone in the city: in 2017 there were fewer than 300 murders in the five boroughs, the fewest since 1951.

"You see the numbers today. The council is here to support the police force, support the de Blasio administration to continue to improve and drive crime even lower," Johnson said.

But Johnson has already signaled that he is willing to put up a fight when he needs to. He has proposed creating an investigative arm with subpoena power for the Council to ensure even tougher oversight of the city.

The mayor is a former councilman himself.

"I found that the tools I had were very very substantial. I think the council has a lot that it can bring to bear right now. But if there are other things they are looking to do, we look forward to talking it through with them," de Blasio said.

The speaker, it was noted, was not mentioned on the mayor's public schedule as attending the event. 

SJohnson also did not hold back when asked if he had policing wish list of his own. 

"One thing that I would like to look at, although I'm not trying to make news here today, this is a discussion I want to have with the mayor, I want to ensure auxiliary officers get bullet-resistant vests as well," he said.

He also voiced general support for the idea of hiring more police officers for the department.

Hiring more police officers is something that could be part of budget negotiations in the spring, which, of course, will be one of the first big tests for Speaker Johnson, and the mayor as well.