CRANSTON, R.I. — Behind the barbed wire and thick walls of the state mental hospital here are two patients who have not been allowed to live in the outside world for 20 years. Both were found not guilty of murder by reason of insanity.

Still, they have voted in elections nearly every two years, casting ballots by mail. Now, however, election officials are taking steps that could ban them from voting, arguing that state law denies the vote to people with such serious psychiatric impairments.

“I just think if you are declared insane you should not be allowed to vote, period,” said Joseph DeLorenzo, chairman of the Cranston Board of Canvassers. “Some people are taking these two clowns and calling them disabled persons. Is insanity a disability? I have an answer to that: no. You’re insane; you’re nuts.”

Rhode Island is among a growing number of states grappling with the question of who is too mentally impaired to vote. The issue is drawing attention for two major reasons: increasing efforts by the mentally ill and their advocates to secure voting rights, and mounting concern by psychiatrists and others who work with the elderly about the rights and risks of voting by people with conditions like Alzheimer’s disease and dementia.