AUGUSTA, Maine — Lawmakers have preliminarily approved a bill that would create a three-tiered system for registered sex offenders but could not agree on a viable risk assessment tool to categorize offenders.

Members of the Criminal Justice and Public Safety Committee on Monday unanimously approved a carry-over bill, LD 1514, that seeks to overhaul the Maine Sex Offender Registry and Notification Act. The bill now goes to the House and Senate for approval.

The centerpiece of LD 1514, sponsored by Rep. Anne Haskell, D-Portland, seeks to create a three-tiered system for registered offenders and employ a risk assessment tool to classify offenders into those tiers.

Under the proposal, offenders would be separated into 10-year registrants, 25-year registrants and lifetime registrants based on the offense.

That tiered system remained in the bill, but Haskell said members were not prepared to include a risk assessment model because risk assessment for offenders is still an evolving issue.

“It’s something we’ll continue to look at. We’re certainly not giving up on it, but it won’t get done this session,” she said.

Rep. Gary Plummer, R-Windham, the House chair of the Criminal Justice and Public Safety Committee, said he was glad his committee voted unanimously on a bill and, like Haskell, he wasn’t ready to give up on risk assessment.

“I think as time goes on and around the country as other legislatures grapple with this, it will become clear that either there is a reliable tool or there isn’t,” Plummer said.

Maine’s Sex Offender Registry and Notification Act was passed in 1999 and has been tweaked but not significantly changed since then even though the Maine Supreme Judicial Court and some lawmakers say it contains inequities.

Last summer, Maine learned that it was one of many states that failed to comply with a federal law, the Adam Walsh Act, that requires states to adopt certain restrictions.

That law, named after a Florida boy who was killed 30 years ago by a sex offender, calls on states to work toward changing their registries in a way that feeds into a national sex offender database. States have voiced concerns about the federal act’s requirements, including how it addresses retroactive punishment.

According to the Department of Justice last summer, states that failed to comply could lose 10 percent of their Byrne Justice Assistance Grant. Maine received more than $1.3 million in funding for 2011 under that program.

By creating the tiered system and including a spot on the registry for juvenile offenders who are tried as adults, Haskell said she believes her bill will bring Maine into compliance with the Adam Walsh Act.

Plummer said juveniles often offend for different reasons than adults, so it’s difficult to justify putting them in the same category. That’s why the committee only supported adding juveniles who are tried as adults.