Callahan asked the Supreme Court Wednesday afternooon to stop the execution.

The Supreme Court on Jan. 7 heard oral arguments in a Kentucky challenge to lethal injection, a case that has delayed executions nationwide. A ruling is unlikely before spring. Alabama uses lethal injection in its executions.

In a 2-1 decision, the Atlanta-based 11th U.S. Circuit Court of Appeals on Tuesday lifted the stay granted by U.S. District Judge Keith Watkins in Montgomery on Dec. 14.

The court said Callahan waited too late to challenge the method of execution.

Callahan, who is now scheduled to die at 6 p.m. Thursday at Holman prison near Atmore, was sentenced to death for the kidnapping, rape and murder of Jacksonville State University student Rebecca Suzanne Howell on Feb. 4, 1982.

Authorities said she was abducted from a coin laundry in Jacksonville and raped before being strangled and dumped in Tallasseehatchee Creek.

In lifting the stay, the 11th Circuit ruling said it did not make any finding on "the relative merits of Callahan's constitutional claim because we conclude the claim is barred by the statue of limitations."

Judges Gerald Tjoflat and Susan Black, forming the majority, said the two-year time deadline began on July 31, 2002, when Callahan selected lethal injection as the method by which he would be put to death. They said he waited more than two years after the deadline expired to challenge lethal injection.

In dissent, Judge Charles Wilson said the time period to file a challenge does not begin "until the prisoner knows or has reason to know the facts giving rise to his claim and the prisoner's execution becomes imminent."

Wilson said the majority's approach "requires a death-sentenced prisoner to file a method-of-execution claim years before his execution is to take place, during which time the challenged protocol could be materially changed."

In his Dec. 14 order, Watkins wrote that the public interest would not be served by an unconstitutional execution, and Callahan's constitutional challenge should be resolved first. The judge said it would be "a waste of judicial resources" to hold a trial on Callahan's suit before the U.S. Supreme Court rules in the Kentucky case.

The state attorney general's office had opposed a stay and appealed to the 11th Circuit.

On Dec. 5, the Supreme Court stopped the execution of another Alabama death row inmate, Tommy Arthur, one day before he was scheduled to die by lethal injection at Holman prison. That stay also stemmed from the pending Kentucky case.