Correction: An earlier version of this story incorrectly stated that Virginia adopted a two-drug combination for lethal injections in 2012. The state adopted a new second drug for its three-drug mixture. The article has been updated to reflect the correct information.

Virginia lawmakers are expected to vote this week to establish the electric chair as the state’s default method of execution when drugs used for lethal injection are not available.

The measure, prompted by a long-standing shortage of the drugs, would make Virginia the only state where a death-row prisoner could be forced in some circumstances to be electrocuted.

The bill has passed the House of Delegates and is expected to emerge from the Virginia Senate this week. A spokesman said Gov. Terry McAuliffe (D) has not taken a position on signing or vetoing the legislation.

The embrace of an execution method largely shunned over the past two decades comes as the death penalty, while still legal in many states and supported by a large if declining majority of Americans, is becoming increasingly difficult to implement.

Across the country, states are struggling to procure the drugs necessary to perform lethal injections. Manufacturers in Europe have refused to sell drugs for use in capital punishment, as has at least one major U.S. manufacturer. The three-drug cocktail used commonly since the Supreme Court reinstated the death penalty in 1976 is now out of reach.

This undated file photo provided by the Virginia Department of Corrections shows an electric chair that Virginia provides as an alternative to lethal injection. (AP)

That has left states to experiment with other drugs. Virginia opted for a new three-drug combination; other states have been moving toward using one large dose of a sedative. But the new options are prompting the same protests from manufacturers as the old ones. And untested formulas have led to complications and court challenges; a man executed in Ohio recently took 25 minutes to die.

Records show that Virginia’s Department of Corrections purchased several doses last fall of the two drugs used in Ohio’s controversial execution, as well as the new three-drug mixture that the state adopted as its official method of lethal injection in 2012.

But in two years of searching, Virginia has not been able to secure a steady supply of either mixture, a corrections official told a Senate subcommittee last month.

“We haven’t found anything yet,” said Debra Gardner, chief deputy director of the Department of Corrections. While the department has no position on the bill, Gardner described electrocution as leaving “minor burns, just barely noticeable.”

State law allows death-row inmates to choose between two methods of execution — lethal injection and electrocution. As in every other state where the death penalty is practiced, Virginia designates lethal injection as the default method when the prisoner declines to choose.

The new law would allow corrections officials to carry out the execution when a prisoner’s choice is not available and when the prisoner declines to choose.

If the law doesn’t pass, or if McAuliffe vetoes it, the shortage of chemicals could eventually lead to a de facto moratorium on the death penalty, with prisoners empowered to block their own executions by demanding a method that is not available.

A mandatory electrocution has not occurred in the United States since the 2002 execution in Alabama of Lynda Block, an anti-government conspiracy theorist who shot and killed a police officer.

Virginia is second to Texas in executions overall and is one of only eight states still operating an electric chair. The state has executed 110 inmates since the death penalty was reinstated. Eight inmates are currently on death row.

State officials approached lawmakers in January with the conundrum.

“They can’t [perform executions] because the default is lethal injection and they have no drug to do it with,” said Sen. Charles W. Carrico Sr. (R-Grayson).

Both critics and supporters predicted this week that the legislation will pass in the Senate.

“I’m going to vote against it, but I suspect it’s going to pass,” said Sen. A. Donald McEachin (D-Henrico).

Three of the last six people executed in Virginia, dating to November 2009, have chosen the electric chair, including two men who were executed for capital murders in Prince William County.

The most recent electrocution in Virginia was last year. Robert Gleason Jr., convicted of murdering two fellow prisoners while serving a life sentence for a drug-related slaying, had threatened to kill again if not given the death penalty.

Supporters of the electric-chair bill have pointed to that successful execution as proof that concerns about the method’s safety are overblown.

“Having been there and watched it, it was not as dramatic as it’s portrayed on television,” said Ron Elkins, the commonwealth’s attorney from Wise County. Still, he said, “I don’t think there’s any question that lethal injection is much more humane as far as the defendant is concerned.”

Elkins conceded that watching an electrocution changed his views. “Before, I was a proponent of the death penalty,” he said. “I’ve limited myself more to applying it on a case-by-case basis” in particularly heinous crimes.

Opposition to the practice remains strong. Courts in Georgia and Nebraska have deemed the electric chair cruel and unusual punishment.

“There’s a credibility issue” in going back to the chair, said Deborah W. Denno, a law professor at Fordham University who specializes in the death-penalty issue. “If electrocution was such a humane method of execution, they would never have switched to lethal injection. No state would have.”

Virginia might be better off pursuing new avenues for drug production, suggested Richard Dieter, executive director of the Death Penalty Information Center. “There are executions occurring regularly” via lethal injection, he said. “It seems like a leap to go to electrocution at this point.”

Virginia’s Supreme Court has not considered the issue since 1921.

Death by electrocution came into use in the late 19th century as states looked for a modern alternative to hanging. Doctors discouraged the idea of death by injection for fear that it would inspire a public aversion to hypodermic needles. Thomas Edison, meanwhile, encouraged the use of alternating current in the development of the chair, hoping that it would show that the rival to his less-powerful direct current was dangerous.

The Supreme Court came close to addressing the issue in 2000 after three botched electrocutions in Florida, changing course only after the state pledged to switch to lethal injection. Before that, the last time electrocution came before the court was in 1890, when justices declined to rule against the practice.

Virginia oversaw a pair of messy executions in the same era, including one in which blood poured from under the prisoner’s leather mask. Those disturbing incidents helped inspire the legislation that made lethal injection the default, as well as a 1991 rewiring of the chair, which is now 104 years old.

Even so, a state lawmaker in Wyoming has introduced similar legislation.

In Missouri, there’s a bill to bring back the firing squad.