New York City has an opportunity to close the dysfunctional jail complex on Rikers Island. But this moment will not last forever.

It has been six months since the Independent Commission on New York City Criminal Justice and Incarceration Reform — a panel convened by City Council Speaker Melissa Mark-Viverito and chaired by me — issued a blueprint for a modernized criminal justice system. It called for reducing the jail population, building state-of-the-art jails near the borough courthouses, and repurposing Rikers for much-needed infrastructure and the potential expansion of LaGuardia Airport. Also, it has been six months since Mayor Bill de Blasio pledged to close to Rikers within a decade.

The political alignment is exceptional, especially in an election year. Not only de Blasio, but also Gov. Andrew Cuomo, prosecutors in the Bronx, Brooklyn and Manhattan, and City Council members who represent potential sites for replacement facilities agree we must close Rikers, which has systemic problems and a culture of brutality.

The consensus is so strong — debate is only on how quickly to close Rikers.

As former chief judge, I ran New York State’s courts for many years. I know how difficult it is to make change; without immediate action, the Rikers debate is moot.

De Blasio has created a Rikers task force and unveiled a plan that includes expanding proven supervised release programs and reducing the cycle of short jail stays caused by problems like homelessness and mental illness.

His plan is a start, but it won’t get us across the finish line. To close Rikers, the city’s successful supervised release programs should be greatly expanded. When defendants are not immediately released, supervised release should be the default for nonviolent felonies and misdemeanors, and an option for some more serious cases. In addition, the city should continue to bolster its pretrial services capacity so that bail determinations don’t inadvertently become jail sentences.

It is also imperative to begin building smaller modern jails near borough courthouses. The misery of Rikers will never end without new facilities, which will be safer for correctional officers and detainees. It is the mayor’s role to plan and budget for the new system.

While Rikers must be closed within 10 years at the outside, the timeline can be shorter. Legislative change in Albany is a must — to reform bail, speed of trials and discovery to ensure that fewer people are jailed because they lack financial resources or because of outmoded court processes.

We are in an election season in NYC, and we all should be prepared to take up the fight to close Rikers. Every minute that passes is another minute detainees and officers must spend in the violent and decrepit jails on Rikers.

When it comes to criminal justice, we should judge our leaders not simply by their statements, but by the practical steps they take to end the penal colony on Rikers Island.

Jonathan Lippman, of counsel at Latham & Watkins LLP, is a former chief judge of the New York State Court of Appeals.