Progressive lawmakers in the State House are urging House leaders to expand the scope of the criminal justice system overhaul set for debate this summer, but their ambitions face a big hurdle in the form of House Speaker Robert DeLeo.

A coalition of left-leaning Democrats are trying to put pressure on the more moderate members of their own party to allow debate on bills to refashion the state's mandatory minimum sentencing laws for drug and nonviolent offenders during the current 2017-2018 legislative session.

The House and Senate already agree with Gov. Charlie Baker on a bill to improve post-release services to reduce recidivism, but Representative Byron Rushing wants to take up bills dealing with the entire justice system this session.

"Reducing incarceration... addressing incarceration conditions and what goes on in prisons, leading to their successful reintegration in our communities as well as the end of reducing recidivism," Rushing said at a press conference Tuesday.

Standing in progressives' way is Speaker Robert DeLeo, who wants to limit what lawmakers do this year to what's already agreed on before moving on to other parts of the justice system.

"I think some of it is going to require some real discussion and some real debate, public hearings, want to hear from folks around the state. So we want to make sure we get it right," DeLeo told reporters Tuesday morning.

The House plans to take up the bill on post-release services this summer.