A federal judge has lifted her court order that temporarily blocked Arkansas from executing two inmates in one night.
Lawyers for Marcel Williams had questioned whether the night's first execution of Jack Jones went properly.
US District Judge Kristine Baker issued the stay for Williams, then, lifted it about an hour later.
It was unclear whether Williams' attorneys would attempt further actions to delay the execution. His death warrant was due to expire at midnight.
An spokesman for the state attorney general said the execution could proceed.
The stay came just minutes before Williams, 46, was scheduled to begin undergoing the lethal injection process and about an hour after Jones, 52, was pronounced dead by state officials.
Williams' lawyers filed a last-minute appeal claiming that Jones was still moving more than five minutes after he received a sedative, midazolam, that is supposed to render inmates unconscious.
Jones was convicted of raping and killing Mary Phillips, 34, in 1995 and trying to murder her 11-year-old daughter. He also was convicted of rape and murder in Florida.
Williams was convicted of the 1997 kidnapping, rape and murder of 22-year-old Stacy Errickson. He also abducted and raped two other women.
The last time a US state executed two people in one day was 2000 in Texas.
Arkansas had scheduled eight executions over an 11-day period before the end of April, when its supply of one lethal injection drug expires. One inmate was put to death last week, though the first three executions were cancelled because of court rulings.