The City Council is set to ban the use of solitary confinement in city jails — setting up a long-anticipated battle between Mayor Eric Adams and the more progressive legislature.

"The reality is no matter what terminology you use, people are facing the cruel and unusual punishment of isolation," Public Advocate Jumaane Williams said at a rally outside of City Hall on Tuesday.

A bill will prohibit the use of solitary confinement, typically seen as isolating a detainee for much of the day. It will allow the Department of Correction to isolate detainees for only four hours at a time in so-called deescalation units if they pose a risk of harm to themselves or others.

"We are here because we are telling our colleagues that we have 38 co-sponsors on this bill," Manhattan City Councilwoman Carlina Rivera said at the rally on Tuesday.

The bill has a veto-proof majority of support. The legislation has been pending at City Council for several years, and been the subject of much controversy.

City Hall argues jails don’t use traditional solitary confinement, but on Rikers Island, there are other types of restrictive housing units for violent detainees where people are isolated.

Those units can keep detainees in their cells for up to 17 hours a day. Advocates have also accused the department over the years of operating units that are even more restrictive.

When asked whether he would veto this bill on Tuesday, the mayor said he was trying to convince councilmembers to vote down the measure.

"I don't like the bills and we're going to continue to talk to councilmembers," Adams said. "What I have found is the idealism collides with realism and the talking points of the bill is different from the operationalizing of a bill."

While advocates and progressive members of the City Council have been pushing for the measure for many years, arguing solitary confinement amounts to torture, the union representing city correction officers has been vigorously fighting for its defeat.

They re-upped a social media campaign this week to urge councilmembers to vote no.

"Basically, what he is calling for is a four-hour time out and that's ludicrous in our system," said Benny Boscio, the head of the Correction Officers' Benevolent Association. "We can't have that. There has to be viable consequences for crimes that are committed in jail."

The legislative fight comes as the fate of Rikers Island is far from certain. A federal judge is in the process of considering whether the jail complex should be taken over by a federal receiver.