Defense lawyers had argued Gore, 50, was mentally ill and executing him for the 1988 murders of two women would violate the U.S. Constitution's ban on cruel and unusual punishment. The court upheld an earlier ruling by Administrative Judge Ysleta McDonald that Gore was faking mental illness, The Miami Herald reported Tuesday.
His original execution date of June 2 had been stayed by the U.S. 11th Circuit Court of Appeal, which lifted the stay three days later. A July 10 execution was delayed after McDonald agreed to hear testimony from a doctor who claimed Gore was mentally ill.
He is now scheduled to die Sept. 10.
Gore was convicted of killing Robyn Novick of Lauderhill and Susan Marie Roark of Tennessee.
Novick was found beaten and stabbed to death in a trash pile near Homestead. Roark's body was found in a rural area in northern Florida.
Gore was arrested after a woman he had left for dead survived after being kidnapped, raped, having her throat slit and beaten with a rock.