ST. LOUIS – With lethal-injection drugs in short supply and new questions about their effectiveness, lawmakers in some death penalty states are considering bringing back relics of a more gruesome past: firing squads, electrocutions and gas chambers.

Most states abandoned those methods more than a generation ago in a bid to make capital punishment more palatable to the public and to a judicial system worried about inflicting cruel and unusual punishments that violate the Constitution.

But to some elected officials, drug shortages and recent legal challenges are beginning to make lethal injection seem too vulnerable to complications.

"This isn't an attempt to time-warp back into the 1850s or the wild, wild West or anything like that," said Missouri state Rep. Rick Brattin, who this month proposed making firing squads an option for executions. "It's just that I foresee a problem, and I'm trying to come up with a solution that will be the most humane yet most economical for our state."

Brattin, a Republican, said questions about the injection drugs are sure to end up in court, delaying executions and forcing states to find alternatives. It's not fair, he said, for relatives of murder victims to wait years to see justice served while lawmakers and judges debate execution methods.

Like Brattin, a Wyoming lawmaker this month offered a bill allowing the firing squad. Missouri's attorney general and a state lawmaker have raised the notion of rebuilding the state's gas chamber. And a Virginia lawmaker wants to make electrocution an option if lethal drugs aren't available.

Move to injections in 1980s

If adopted, those measures could return states to the harrowing imagery of previous decades, when inmates were hanged, electrocuted or shot.

States began moving to lethal injection in the 1980s in the belief that powerful sedatives and heart-stopping drugs would replace the violent spectacles with a more clinical affair while limiting, if not eliminating, an inmate's pain.

The total number of U.S. executions has declined in recent years — from a peak of 98 in 1999 to 39 last year. Some states have turned away from the death penalty entirely.

In recent years, European drugmakers have stopped selling the lethal chemicals to prisons because they do not want their products used to kill.

At least two recent executions are also raising concerns about the drugs' effectiveness. Last week, Ohio inmate Dennis McGuire took 26 minutes to die by injection, gasping repeatedly as he lay on a gurney. And on Jan. 9, Oklahoma inmate Michael Lee Wilson's final words were, "I feel my whole body burning."

Missouri threw out its three-drug lethal injection procedure after it could no longer obtain the drugs. State officials switched to propofol in 2012.

Limits on drug exports

The anti-death penalty European Union threatened to impose export limits on propofol if it were used in an execution, jeopardizing the supply of a common anesthetic needed by hospitals. In October, Gov. Jay Nixon stayed an execution and ordered the Missouri Department of Corrections to find a new drug.

Days later, the state announced it had switched to a form of pentobarbital made by a compounding pharmacy.

Michael Campbell, assistant professor of criminal justice at the University of Missouri-St. Louis, said some lawmakers simply don't believe convicted murderers deserve any mercy.

"Many of these politicians are trying to tap into a more populist theme that those who do terrible things deserve to have terrible things happen to them," Campbell said.

Richard Dieter, executive director of the Death Penalty Information Center in Washington, D.C., cautioned that there could be a backlash.

"These ideas would jeopardize the death penalty because, I think, the public reaction would be revulsion," he said.

Some states already provide alternatives to lethal injection. Condemned prisoners may choose the electric chair in eight states: Alabama, Arkansas, Florida, Kentucky, Oklahoma, South Carolina, Tennessee and Virginia. Inmate Robert Gleason Jr. was the most recent to die by electrocution, in Virginia in January 2013.

Arizona, Missouri and Wyoming allow for gas-chamber executions. Delaware, New Hampshire and Washington state allow inmates to choose hanging. The last U.S. hanging was in Delaware in 1996.

Utah is phasing out its use, but the firing squad remains an option there for inmates sentenced before May 3, 2004.

The firing squad is an option in Oklahoma, but only if lethal injection and electrocution are found unconstitutional.

Jackson Miller, a Republican in the Virginia House of Delegates, wrote a bill that would allow electrocution if lethal injection drugs are unavailable.

Miller said he would prefer that the state have easy access to the drugs needed for lethal injections. "But I also believe that the process of the justice system needs to be fulfilled."