The Maine Senate on Tuesday rejected a bill to create opioid harm reduction centers, instead advancing an amendment to study the issue.

The Senate voted down the House-approved bill to allow the centers 18-16, with at least one Democrat expressing concern about the legality of the facilities.

Sen. Joe Baldacci (D-Bangor) called the measure a “backdoor decriminalization bill” saying that any cities or towns that opted to allow the facilities would be “committing a federal crime.”

Last week House advanced the bill, 77-66, that would have allowed cities and towns to decide whether to allow so-called safe injection sites where those with substance use disorder can inject illegal drugs with medical supervision.

Rep. Grayson Lookner (D-Portland) is sponsoring LD 1364, which requires that the harm reduction centers be approved by a municipality. They must provide clean facilities, safe disposal of needles, the overdose-reversing drug Narcan, and medical and social services.

The bill also provides immunity from arrest or prosecution for clients and staff at the sites.

Last year, an estimated 715 Mainers died of drug overdoses, the third straight record-setting year.

From January through April this year, 201 fatal overdoses have been recorded, according to the Maine Drug Data Hub. By comparison, 215 overdoses were reported in the same period last year.

Gov. Janet Mills has not yet taken a public position on the bill, but her administration opposed it during a public hearing in April.

The bill now heads back to the House, where it will consider whether to accept the Senate’s amendment to study the issue.