Mayor de Blasio is on board with a soon-to-be-released plan to close Rikers Island, he announced at a City Hall press conference this afternoon. The New York Times obtained a draft of the plan drawn up by an independent commission, headed by retired New York state Chief Judge Jonathan Lipmann and assembled at the request of the City Council last year.

De Blasio met with Lipmann and Council Speaker Melissa Mark-Viverito on Thursday evening. At the press conference Friday, he claimed not to have seen a copy of the report, which he said would be published Sunday. Instead, he said, he and Mark-Viverito had reached an agreement on the benchmarks that would need to be met to phase out the use of Rikers over the next 10 years, replacing some of that jail capacity with new facilities around the city. He stressed that he does not know what potential locations are under consideration for placing new jails.

The hastily organized press conference came without the kind of written materials that typically accompany a major City Hall announcement.

Between yesterday evening and this morning, according to de Blasio, "We said, 'Wait this is the combination of factors that would actually make this work.' We thought, it’s time to go ahead and make the announcement that we had an agreement on how this would work."

He said that the aim is to get the city jail population, currently at around 9,300, to 5,000 in the next decade. By the time the population reaches 7,000, he said, new jails would have to be sited and moving towards construction for the transition to work.

Our pals over at DNAinfo broke the news of the plan, and the mayor's involvement in looking into it, a year ago. At the time, de Blasio denied the existence of a search for an alternative to Rikers and called it a "noble concept" that couldn't be done.

The Times reports that the nearly-finished study calls for phasing out the use of Rikers over 10 years as the city further slashes the jail population through bail reforms, expanded diversion programs for drug offenders and the mentally ill, and changing state law so that some low-level offenses such as fare evasion and "gravity knife" possession are handled in civil court. In the place of the island jail complex, the city would build new jails in each of the boroughs to hold as many as 5,500 prisoners, as compared to the 9,000-10,000 in the system currently.

Advocates for closing Rikers have long argued that such an arrangement would lower costs by moving inmates closer to the courts, and make it easier for prisoners' families and attorneys to visit. However, the prospect is an extremely heavy lift politically, requiring billions of dollars in construction, laying off thousands of members of the politically influential Correction Officers Benevolent Association, and instigating fights with NIMBY activists and local politicians in districts across the city.

Department of Correction Commissioner Joseph Ponte claimed, improbably, that jailers and their union reps would not oppose the plan, saying, "I don’t think anybody would argue with a safer, more humane correctional system."

A spokesman for the union did not immediately respond to a message seeking comment.

Mark-Viverito has been a strong backer of the proposal as Council speaker.

"After decades of a system that wants to strip away the dignity of human beings that happen to have an interaction with the criminal justice system," she said this afternoon, citing the suicide death of Kalief Browder, who spent three years on Rikers, most of the time in solitary, before having his charges of stealing a backpack dropped. "We finally have someone who wants to give some back."

One of many outstanding questions is whether it would make sense to build a new facility on Rikers in the interim. The Bloomberg administration approved and designed a $660-million new facility on the island. Its future is now in question, but de Blasio said, "Nothing's off the table" until the 5,000-inmate mark is reached.

The city currently has jails in lower Manhattan and Downtown Brooklyn that together hold around 2,400 people.

Asked whether he wasn't setting up arbitrary benchmarks to avoid blame when he's out of office and the plan doesn't work out, de Blasio told a reporter, "That's your interpretation. That's not what I feel."

He continued, "Political benefit would be saying we’re closing Rikers next year and the Mexicans are paying for it. You think this is pandering, but I know real pandering. Real pandering would be saying I’m closing rikers next year and it’s not going to affect you at all. What i said was to give everyone a sense of the trajectory that must be met."

Mark-Viverito and de Blasio praised themselves for enacting various reforms, including ending solitary confinement for people under 21 and providing video visitation for inmates. They also claimed that hiring 2,000 extra cops to engage in "neighborhood policing" has helped contribute to the crime rate decline of the last three years. The mayor said that the last year's, and even the last month's crime numbers helped convince him that the closure was possible. The drop continues a two-decade-long trend.

Robert Gangi, outgoing director of the Police Reform Organizing Project and soon-to-formally-announce long-shot mayoral candidate, said that closing Rikers wouldn't require building new jails if city leadership reformed the police department's use of Broken Windows policing.

"They address the conditions on the back end, as opposed to the front end, which is what’s causing mass incarceration," he said, noting that the Queens House of Detention has been decommissioned but could be renovated for less than what it would cost for several new jails. "There are ways to reduce the city’s jail population [that] the city is not willing to undertake, which are discriminatory policing practices. They drive the city’s jail population more than any other thing."

De Blasio has been an ardent defender of the strategy, which overwhelmingly is carried out against black and Latino men and is a signature of former police Commissioner Bill Bratton. The NYPD Inspector General's Office found in a study last year that there is no meaningful statistical correlation between concerted low-level enforcement and decreases in felony crime. Bratton disputed the report's findings but did not offer any substantive critiques of its methods. The NYPD has refused to make most of the reforms called for by the report to better assess the effectiveness of the methods.

Post-jail-demolition, Rikers Island would make a good spot for a LaGuardia runway expansion or some other infrastructure facility, the report reviewed by the Times said. The noise and height restrictions related to the nearby airport would make it unfeasible for housing.

"We fully intend to reutilize Rikers Island for purposes other than jailing people," de Blasio said. "Government facility, private-sector enterprises—whatever it may be, there’s going to be a second life for Rikers Island."

This post has been updated.