A condemned child killer was scheduled to die on Wednesday in the state's first execution in more than three years after the U.S. Supreme Court denied his requests for more time to pursue legal challenges.

Ronald Phillips was transported to the death house at the Southern Ohio Correctional Facility in Lucasville on Tuesday morning, about 24 hours before his execution was planned. He was convicted of the 1993 rape and killing of his girlfriend's 3-year-old daughter in Akron.

Justices denied the 43-year-old Phillips a stay on three requests, with a pair of justices dissenting on a request by Phillips that was joined by two other death row inmates with upcoming execution dates. The inmates had asked the court for a delay while they continue challenging Ohio's new lethal-injection method.

Justices Sonia Sotomayor, joined by Justice Ruth Bader Ginsburg, dissented, arguing the inmates had demonstrated a likelihood of success at trial. Sotomayor objected to the court's "failure to step in when significant issues of life and death are present."

The death penalty has been on hold in Ohio since January 2014, when a condemned inmate repeatedly gasped and snorted during a 26-minute procedure with a never-before-tried drug combination. Republican Gov. John Kasich halted upcoming executions after that, and delays have continued because the state had trouble finding new supplies of drugs and death row inmates sued on the grounds the state's proposed new three-drug execution method represented "cruel and unusual punishment."

Phillips' arguments were backed up by 15 pharmacology professors, who stepped in Monday to argue that a sedative used in the process, midazolam, is incapable of inducing unconsciousness or preventing serious pain.

A federal court last month upheld the use of midazolam, which has been problematic in several executions, including Ohio's in 2014 and others in Arkansas and Arizona.