Nebraska’s death penalty will stay on the books until voters decide next year whether to keep it, the state’s top election official has said.

John Gale, the secretary of state, said on Friday that death penalty supporters have gathered enough valid signatures to prevent a law repealing capital punishment from going into effect until the November 2016 election.

Nebraska lawmakers abolished the death penalty in May, prompting a petition drive for a ballot measure to overturn their decision. The issue had already qualified for the ballot, but Friday’s announcement confirms that the petition drive also succeeded in postponing the repeal.

The group Nebraskans for the Death Penalty said it planned to begin a “Repeal the Repeal” campaign urging voters to keep capital punishment. Campaign leaders will “work to ensure that Nebraska voters have their voice heard on this important criminal justice issue”, spokesman Chris Peterson said.

A spokesman for the anti-death penalty Nebraskans for Public Safety said his group will continue its outreach efforts to voters.

“Nebraska voters will have the same opportunity the legislature did to have a thoughtful discussion on whether to bring back a failed system that hasn’t been used in nearly two decades, is not a deterrent, and is a waste of taxpayer dollars,” spokesman Dan Parsons said.

Death penalty opponents also have filed two lawsuits challenging the ballot measure. One lawsuit alleges the measure is invalid because governor Pete Ricketts should have been listed as a sponsor of the $900,000 petition drive.

Campaign filings showed Ricketts, a Republican who supports capital punishment, donated $200,000 to Nebraskans for the Death Penalty after lawmakers overrode his veto of the repeal. Some of the group’s managers also are his close political allies. Ricketts has denied that he was a sponsor.

Another lawsuit argues that language approved by Republican attorney general Doug Peterson’s office is slanted in favor of death penalty supporters, because it incorrectly implies that first-degree murder convicts could face a lesser sentence than life in prison if the death penalty is repealed. Peterson’s office has said the language is clear, fair and impartial.

Petition sponsors needed nearly 114,000 signatures to suspend the repeal and place it on the ballot, in addition to meeting signature thresholds in at least 38 of Nebraska’s 93 counties. Gale said county election officials verified more than 143,000 signatures, and the petition circulators met the minimum signature threshold in 85 counties.

Nebraska hasn’t executed an inmate since 1997, and the state currently lacks two of the three drugs in its protocol. The department of correctional services spent more than $54,000 to buy the drugs from a supplier in India, but the US Food and Drug Administration said they can’t be legally imported. Nebraska currently has 10 men on death row.