LINCOLN, Neb. — A Nebraska lawmaker who is running for governor filed a federal lawsuit Thursday to overturn a state law that imposes the nation’s highest bar on independent candidates to qualify for statewide races.

Sen. Bob Krist of Omaha said he will challenge the 2016 law that substantially raised the signature requirement for nonpartisan candidates to get on the ballot.

Krist, a self-described centrist, switched his party affiliation from Republican to nonpartisan in September and mounted a campaign against incumbent GOP Gov. Pete Ricketts, who is seeking re-election.

The lawsuit argues that the state has imposed an undue burden on Krist and voters who support him, in violation of their constitutional rights to free speech and equal protection. Four voters are also listed as plaintiffs, including former state Sen. Al Davis, a moderate Republican who lost his seat in 2016.

The law in question requires nonpartisan candidates in statewide elections to collect signatures from at least 10 percent of the state’s registered voters, or about 119,000 voters. Before it passed, candidates needed just 4,000 signatures to qualify for the ballot, with at least 750 coming from each congressional district.

“It simply is another roadblock that the parties would put in place to push back on any independent to have a credible run at any office in the state,” Krist said at a news conference at the Capitol.

No other state has a signature threshold as high as Nebraska’s, said Dave Domina, an Omaha attorney who is representing Krist and his supporters. Thirty-seven states require 10,000 signatures or fewer to place independent candidates on the ballot. Domina said lawmakers failed to show any compelling state interest to demonstrate why the 2016 law was needed.

“I’m glad this issue is going to be presented to the United States District Court,” Domina said.

The lawsuit was filed against Nebraska Secretary of State John Gale, who administers the state’s election laws. A spokeswoman for the secretary of state’s office declined to comment.

Krist has said he will run as a third-party candidate, an approach that requires signatures from roughly 5,700 voters. But on Thursday, he said he wanted to keep his options open. Krist said he viewed the bill as an “injustice” that needed to be corrected regardless of how he chooses to run.

“Access to the ballot needs to be reasonable,” Krist said.

Lawmakers approved the higher requirement in 2016 as part of an omnibus election-law bill without debating it on the floor of the Legislature. The bill’s Republican sponsor, Sen. John Murante of Gretna, was the only person to testify on the measure during a committee hearing earlier that year.

Several senators, including Krist, have since acknowledged that they didn’t realize the higher signature requirement was included in the bill. The measure passed 45-0 in the session’s final days, a time when many lawmakers are tired and scrambling to pass a flurry of last-minute bills.

Murante, who is running for state treasurer, noted that the bill passed with bipartisan support and argued that senators had plenty of opportunities to stop it. He also defended the bill, saying it levels the playing field between independent candidates and party nominees who often face a rigorous primary campaign.

“If there are 200,000 people going to the polls and it takes 100,000 votes to actually get the nomination in a primary, the number of signatures to get on the ballot by petition ought to be roughly comparable,” he said.

Sen. Justin Wayne of Omaha introduced a bill this year that would restore the original signature requirement, making it easier for independent candidates to qualify, but its prospects are unclear. The bill was sent to the Government, Military and Veterans Affairs Committee, which Murante leads.

Wayne said some senators are also concerned about setting election policy in an election year.

“If we’re supposed to be a nonpartisan Legislature, I think we should set the tone for the rest of the state to be nonpartisan,” Wayne said.

The Nebraska Republican Party issued a statement Thursday criticizing Krist, who has frequently clashed with the party.

“This is further proof that Bob Krist will do and say anything to try to become governor,” said Kenny Zoeller, the party’s executive director.

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