VARNER, Ark. — The State of Arkansas is scheduled to put two inmates to death on Monday night, setting up what would be the United States’ first double execution in more than 16 years.

Jack H. Jones, Jr., 52, is scheduled to die at the Cummins Unit, a prison in southeast Arkansas, at 7 p.m. local time. He has admitted to raping, beating and strangling Mary Phillips in 1995, and to choking her 11-year-old daughter to unconsciousness.

Marcel Williams, 46, is scheduled to die afterward. Mr. Williams kidnapped, robbed, raped and strangled Stacy Errickson in 1994, and has also admitted guilt.

On Monday, the Arkansas Supreme Court and the United States Court of Appeals for the Eighth Circuit, in St. Louis, denied a range of last-minute requests to halt the executions. Appeals are now pending before the United States Supreme Court.

Arkansas had planned to put eight men to death in 10 days, which would have been the quickest succession of executions in the United States in more than half a century. It was an extraordinary pace at a time when use of the death penalty is in decline, with only 20 death sentences carried out nationwide in 2016, the lowest figure in decades. The last state to put more than one inmate to death in a day was Texas, in August 2000.

What drove the accelerated schedule was that the state’s store of midazolam, one of the drugs used in its lethal injections, was set to expire at the end of April, and states have had trouble acquiring new supplies.

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Like several other states, Arkansas uses a three-drug combination in its lethal injections, but in recent years, drug companies have refused to sell their products for the purpose of executions. The first drug used is midazolam, a sedative intended to render the inmate unconscious, though critics contend that it is not always effective. The second drug is a paralytic to halt breathing, and the third stops the heart.

A flurry of legal challenges in state and federal courts followed news of the state’s capital punishment schedule, and four of the eight executions were stayed by the courts. Last Thursday, the state carried out the execution of Ledell Lee, 51, for the murder of Debra Reese, who was sexually assaulted and clubbed to death in 1993. Mr. Lee, the first inmate executed in Arkansas since 2005, maintained his innocence.

In the days before Monday’s scheduled executions of Mr. Williams and Mr. Jones, their lawyers challenged the use of midazolam. They argued that the two inmates’ particular medical conditions made it likely that the sedative would be ineffectual, making the executions unconstitutionally painful.

A Federal District Court judge in Little Rock, Kristine G. Baker, ruled against the condemned men, whose lawyers appealed to the Eighth Circuit. Judge Baker also ruled against the inmates in a separate challenge over when the curtains to the death chamber should be opened, allowing witnesses in an adjoining room to view the execution.

Their lawyers appealed that, too, to the Eighth Circuit, but the appellate court turned down the appeal on Monday.

In 1995, Mr. Jones raped, beat and strangled Mary Phillips, who was 34, and beat and choked her 11-year-old daughter, Lacy, to unconsciousness, but the girl survived. He has admitted guilt and said repeatedly that he did not want clemency.

Mr. Williams kidnapped, robbed, raped and strangled Stacy Errickson in 1994, and has also admitted his guilt. Ms. Errickson, 22, had two children.

Another inmate, Kenneth Williams, is scheduled for execution on Thursday.

Mr. Williams killed a cheerleader at the University of Arkansas at Pine Bluff in December 1998 but escaped from a maximum-security prison after a jury sentenced him to life the next year. A few miles from the prison, he fatally shot Cecil Boren, a farmer who was working in the yard while his wife was at church, and stole his truck. Mr. Williams led the police into Missouri in a high-speed chase before he crashed into a car, killing the driver. In 2005, he confessed to killing a 36-year-old man the same day he shot the cheerleader.