The Maine Senate likely doomed Gov. Paul LePage’s plan to house violent psychiatric patients at the Maine State Prison after opposing it by just one vote on Wednesday.

The Republican governor’s proposal drew heat from advocates as a violation of patients’ civil rights after it was announced in February, but it’s a response to issues at Riverview Psychiatric Center, which was decertified by the federal government in 2013.

LePage wants to move violent patients at the hospital to a 32-bed unit at the Maine State Prison in Warren that now treats people with mental illnesses in the state’s prison and jail systems.

But if it passed, the state would likely face a legal challenge: Daniel Wathen, the former Maine Supreme Judicial Court chief justice overseeing Maine’s compliance with a settlement in a 1989 lawsuit over mental health services, said LePage’s plan might violate that decree.

The Legislature rejected a similar attempt from LePage in 2013 and looks poised to do it again, with the Republican-led Senate voting 18-17 against their party’s version of the bill, which includes a sunset provision on the state’s authority to house patients in Warren.

The Senate ended up concurring with a Democratic version of the bill passed by the House of Representatives on Tuesday, which requires the LePage administration to develop a separate facility to handle violent patients and holds that they must be placed in state hospitals or Medicare- or Medicaid-eligible facilities.

Three Republicans — Roger Katz of Augusta, Brian Langley of Ellsworth and David Woodsome of North Waterboro — voted with minority Democrats to pass the bill, which faces further votes.

Sen. Eric Brakey, R-Auburn, the committee co-chairman who backed the Republican version of the bill, said it’s necessary to prevent assaults that could endanger patient and staff lives at Riverview, though it’s not an “ideal solution” and the sunset provision was important.

But Katz said it “seeks to turn patients into prisoners” and puts the state at risk of lawsuits.

“If it’s wrong to do it for a long period of time, it’s wrong to do it for a short period of time,” he said.