(CNN) Ohio Gov. Mike DeWine postponed the execution of a death row inmate amid struggles to find a company that will provide the state with drugs for a new lethal injection protocol.

Warren Henness was scheduled to be executed on September 12, DeWine's office said. His new execution date is May 14, giving officials about nine months to come up with a solution.

Prison officials are finding it impossible to locate a supplier of drugs for an execution method to replace a protocol deemed cruel and unusual punishment by a judge, DeWine's office said.

Ohio Governor Mike DeWine said companies are cutting off drug supplies to the state.

US Magistrate Judge Michael R. Merz ruled in January that the dose of the sedative midazolam used in the state's three-drug protocol would not render Henness sufficiently unconscious to prevent "severe pain and needless suffering."

Merz likened the effects of midazolam to "waterboarding" and said the protocol amounted to cruel and unusual punishment in violation of the Eighth Amendment.

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