Updated

The Missouri Supreme Court and Gov. Jay Nixon continued Monday to weigh requests to halt the execution of Joseph Paul Franklin, with time dwindling before the serial killer is scheduled to be put to death.

Franklin, 63, faces execution one minute after midnight on Wednesday. It would be the first in Missouri in nearly three years and the first ever using a single execution drug, the sedative pentobarbital.

Franklin was convicted of killing 42-year-old Gerald Gordon in a sniper attack outside a suburban St. Louis synagogue in 1977. It was one of as many as 20 killings committed by Franklin, a white supremacist who targeted blacks and Jews in a cross-country killing spree from 1977 to 1980. He was convicted of seven other murders but the Missouri case was the only one resulting in a death sentence.

Franklin declined multiple interview requests.

It wasn't clear when Nixon would rule on clemency. His spokesman, Scott Holste, said the governor did not yet have anything to announce. Meanwhile, Franklin's attorney, Jennifer Herndon, said she was still awaiting a ruling from the Missouri Supreme Court.

Last month, Nixon stopped the execution of another convicted killer, Allen Nicklasson, over concerns about Missouri's plan to use propofol as the lethal drug. The European Union had threatened to limit export if propofol was used in the execution, potentially creating a nationwide shortage of the popular anesthetic.

The Missouri Department of Corrections revised its protocol days later, changing to pentobarbital that will be made through a compounding pharmacy. Because the compounding pharmacy is part of the execution team, few details about it have been made public.

Herndon last week filed a motion for a stay of execution with the Missouri Supreme Court, citing concerns about how the drug is made and what could happen if it doesn't work properly, potentially leaving the inmate in pain or brain-damaged but not dead.

Amid court cases and the shortage of execution drugs, Missouri has executed just two men in the past eight years — most recently Martin Link in February 2011.

Herndon said Franklin, a paranoid schizophrenic, now regrets his crimes, having had a change of heart after serving time alongside black inmates.

Franklin was in his mid-20s when he began drifting across America 36 years ago, robbing up to 16 banks to fund his travels.

He bombed a synagogue in Chattanooga, Tenn., in July 1977. No one was hurt, but the killings began soon after that, many of them sniper shootings. Franklin has claimed as many as 20 victims.

He had a particular dislike for interracial couples — several of his victims were black men and the white women with them.

He arrived in suburban St. Louis and picked out Brith Sholom Kneseth Israel synagogue from the Yellow Pages. On Oct. 8, 1977, a bar mitzvah ended and guests were on the parking lot when Franklin opened fire from a grassy area nearby, killing Gordon.

Franklin got away and committed a string of other killings in several other states. He was caught after killing two young black men who were about to go jogging with two teenage white girls in Salt Lake City in August 1980. Years later, in federal prison, he admitted to the St. Louis County killing. He was sentenced to death in 1997.

In addition to the killings, Franklin has admitted shooting and wounding civil rights leader Vernon Jordan and Hustler magazine publisher Larry Flynt.

Flynt, paralyzed from the waist down since the shooting in 1978, has also sued to stop the execution, telling The Associated Press he does not believe it is a deterrent.