AUGUSTA — A proposal from Gov. Paul LePage to place violent patients with mental illnesses at the Maine State Prison ran into stiff resistance after its Monday roll-out.

Jenna Mehnert, the executive director of NAMI Maine, condemned the plan in harsh terms, saying the group was “flabbergasted,” “shocked” and “horrified” at the plan, which she called “criminalization of mental illness.”

It’s LePage’s response to problems at the Riverview Psychiatric Center, the state-run hospital on Augusta’s east side that was decertified by the federal government in 2013 and is struggling with staffing shortages that a watchdog has said puts patients and staff at risk.

The Maine Department of Health and Human Services said Monday that its proposal would allow it to move violent patients at the hospital to a 32-bed unit at the state prison in Warren that opened in 2014 with support from advocates to treat people in Maine’s prison and jail systems with mental illnesses.

But the proposed move, sponsored on LePage’s behalf by Rep. Deborah Sanderson, R-Chelsea, would open it to patients who aren’t incarcerated — particularly those who were deemed not guilty of criminal acts or unfit for trial because of their mental illnesses.

In a statement, DHHS Commissioner Mary Mayhew pitched it as a way to fight “a ripple effect” across Maine’s mental health system occurring when Riverview often has to shut down beds to deal with violent patients, leaving people who should be there in emergency rooms seeking treatment.

It’s not new: LePage wanted the mental health unit to house those types of patients when he asked for it in 2013, but that was stripped out of the bill by the Legislature before it passed. In a statement, the governor said, “Riverview may be in a different place today” if it became law then.

“This bill is a chance for the Legislature to help improve the situation at Riverview,” he said.

But it’s likely to meet strong opposition: Rep. Drew Gattine, D-Westbrook, who co-chairs the Legislature’s Health and Human Services Committee, called it “exactly the wrong approach” and said it’s “almost certainly” a violation of patient civil rights.

He said the state should focus on improving the situation at Riverview rather than moving patients to prison and that “people who have mental illness need to be treated in a health facility, not a correctional facility.”

The administration’s release noted that advocacy groups like Mehnert’s supported the Warren unit. She said while it has been successful at treating people in jail settings, a 10- to 12-bed unit overseen by DHHS would be more appropriate for these patients.

“We cannot take people who are not criminally responsible and put them in the criminal justice system,” she said. “We cannot do it — morally, legally, rationally.”