PROVIDENCE — House lawmakers have approved a proposal that would allow prisoners to earn extra time off their sentences for good behavior, but have eliminated the provision that would award credit for participation in rehabilitation programs.

If OK’d by the Senate in its revised format, the plan will reduce Rhode Island’s swelling prison population and stem costs, but savings would undoubtedly fall short of the projected $1 million that the state is counting to help close next year’s $384-million budget deficit.

In the hours after last night’s vote, lawmakers and prison officials acknowledged that savings would be sacrificed, but could not yet provide specific estimates. “We will have to recast our assumptions about savings,” Corrections Director A.T. Wall said.

Wall said he has concerns about the amended legislation, namely that it removes incentives for prisoners to participate in rehabilitation and treatment programs that could prevent recidivism and ensure public safety.

“It is important to public protection that inmates work on the behaviors that cause them to commit crimes in the first place,” he said.

By law, prison officials cannot force inmates to take part in treatment courses, which is why Wall and others believe it is critical to provide incentives. “I would rather have an offender released several weeks early and know they had dealt with their propensity to commit crime than to have them released without being treated,” Wall said.

Ironically, it was public-safety concerns that prompted House leaders to recast the proposal at the last minute. The original version of the bill prohibited sex offenders from earning time off their sentences for good behavior, but allowed them to earn credit for participation in rehabilitation programs.

A handful of legislators objected, saying any policy that gave sex offenders a chance to get out of prison early was a bad idea.

Last night several of those critics reversed course and voted in favor of the amended legislation, which passed 56-9.

Wall said he was heartened to see at least one piece of the bill move forward to create more parity at the Adult Correctional Institutions and bring Rhode Island in line with other states. The current policy makes inmates serving longer sentences eligible for more time off than those serving shorter stays for less-serious crimes. The change would create a more equitable system, offering most inmates the chance to earn up to 10 days off their sentences per month for good behavior.

In an interview earlier this week, Superior Court Presiding Justice Joseph F. Rodgers Jr., who sat on the joint committee that helped draft the legislation, said the issue of parity is an important one. “A robber sentenced to 16 years in jail is entitled to good-time credit, so why wouldn’t a shoplifter or someone driving on a suspended license who is only serving 3 months not be?” he said. “Fundamentally, it’s a question of fairness.”

Following last night’s vote, bill sponsor John Patrick Shanley, D-South Kingstown, said he plans to submit legislation that would again propose giving sex offenders the chance to earn time off their sentences for program participation.

Designed by a working group representing all three branches of government, and proposed in an unusual accord by the governor’s office and the House leadership, the original plan was intended to alleviate the nearly 4,000 strong prison population and ensure that state prisons don’t hit a court-imposed population cap.

Prison officials initially estimated that the policy change could reduce the average daily census by about 211 next year. No revised estimates were available following yesterday’s amendment.

The Senate has not yet scheduled a hearing on the proposal, but is expected to do so in the coming days.

cneedham@projo.com