Less than 24 hours before his planned execution in Missouri, options were dwindling for white supremacist serial killer Joseph Paul Franklin.

Franklin is scheduled to die at 12:01 a.m. Wednesday for killing a man in a sniper attack outside a St. Louis-area synagogue in 1977. It was one of as many as 20 killings committed by Franklin, who targeted blacks and Jews in a cross-country 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.

On Monday, Missouri Gov. Jay Nixon refused to halt the execution, calling Franklin's crime in Missouri a "cowardly and calculated shooting."

The execution would be the first in Missouri in nearly three years.