LINCOLN, Neb. -- Nebraska lawmakers gave final approval on Wednesday to a bill abolishing the death penalty that would make it the first conservative state to do so since 1973 if the measure becomes law.

The vote margin in the unicameral Legislature was more than enough to override a promised veto from Republican Gov. Pete Ricketts, a staunch supporter of capital punishment, who said that it was a "dark day" for public safety.

"Nebraska has a chance to step into history -- the right side of history -- to take a step that will be beneficial toward the advancement of a civilized society," said Sen. Ernie Chambers, an independent who has fought for four decades to the end the death penalty.

The Nebraska vote marks a shift in the national debate because it was bolstered by conservatives who oppose the death penalty for religious reasons, cast it as a waste of taxpayer money and question whether government can be trusted to manage it. Traditionally, law-and-order conservatives in the United States have stood among the strongest supporters of the ultimate punishment.

Nebraska hasn't executed a prisoner since 1997, and some lawmakers have argued that constant legal challenges will prevent the state from doing so again.

"It's certainly a matter of conscience, at least in part, but it's also a matter of trying to be philosophically consistent," said Sen. Laure Ebke. "If government can't be trusted to manage our health care ... then why should it be trusted to carry out the irrevocable sentence of death?"

Ricketts has promised to veto the bill, requiring an override vote likely to take place next week. The governor announced last week that the state has bought new lethal injection drugs to resume executions.

"This is a case where the Legislature is completely out of touch with the overwhelming majority of Nebraskans that I talk to," Ricketts said.

Ricketts, who is serving his first year in office, argued in his weekly column Tuesday that the state's inability to carry out executions was a "management problem" that he is committed to fixing.

Maryland was the last U.S. state to end capital punishment, in 2013. Three other moderate-to-liberal states have done so in recent years: New Mexico in 2009, Illinois in 2011, Connecticut in 2012. But the last conservative state to do so was North Dakota in 1973. The death penalty now is legal in 32 states, including Nebraska, and the federal government.

Associated Press writer Anna Gronewold contributed in Lincoln.