‘Prove Mike Wrong’ for $5 Million, Lindell Pitched. Now He’s Told to Pay Up.

Mike Lindell, the MyPillow founder and Trump ally who has been a leading voice in pushing conspiracy theories about the 2020 presidential election, must pay $5 million to a software forensics expert who debunked a series of false claims as part of a “Prove Mike Wrong” contest, an arbitration panel said on Wednesday.

Mr. Lindell issued the challenge at a “cyber symposium” in South Dakota in 2021, saying he had data that would support his claims that there was Chinese interference in the election and offering the seven-figure prize to anyone who could prove the data had no connection to the 2020 election.

Because the software expert Robert Zeidman successfully did so, the panel, composed of three members of the American Arbitration Association, ordered that Mr. Lindell would have to pay up.

“Almost everyone there was pro-Trump, and everyone said, ‘This data is nonsense,’” Mr. Zeidman said in an interview on Thursday, identifying himself as a Republican who voted twice for former President Donald J. Trump. “A false narrative about election fraud is just really damaging to this country.”

The ruling against Mr. Lindell was earlier reported by The Washington Post.

Mr. Zeidman, 63, who is from Las Vegas, filed the arbitration claim against Mr. Lindell in November 2021 after the contest’s organizers rejected his findings. The claim was filed in Minnesota, Mr. Lindell’s home state.

The arbitrators ordered him to pay Mr. Zeidman within 30 days.

Mr. Lindell, who has spent millions of dollars on partisan reviews of voting data and efforts to bolster election skeptics across the country, vowed in an interview to challenge the panel’s ruling.

“This is disgusting,” he said. He questioned Mr. Zeidman’s credentials and mused about how he had been granted admission to the symposium.

Mr. Zeidman, who described himself as a “well-known” pioneer in the field of software forensics, said that he used his connections in the Trump world to obtain an invitation to Mr. Lindell’s symposium.

“Friends of mine said, ‘You should go because you might win $5 million,’” he said.

When conference organizers gave Mr. Zeidman and other attendees data to dissect, he said that he expected it might take weeks to analyze. But once he started going through the files, he said he quickly concluded that the data was bogus. He presented his findings to Mr. Lindell’s representatives in a 15-page report.

The $5 million claim against Mr. Lindell is a pittance compared with a pending $1.3 billion defamation lawsuit that the election equipment company Dominion Voting Systems filed against him in 2021 over his assertions that its machines were part of a plot to steal the election. This week, the company reached a $787.5 million settlement with Fox News as part of a similar defamation lawsuit.

Brian Glasser, a lawyer for Mr. Zeidman, cast doubt on whether Mr. Lindell would be able to successfully challenge the arbitration decision in court, saying the bar was particularly high. Mr. Lindell would have to prove “manifest injustice,” a legal term for an unduly harsh outcome, he said.

Mr. Glasser also noted that the contest rules set by Mr. Lindell prescribed binding arbitration in the event of a dispute.

Still, Mr. Lindell insisted: “It’s going to end up in court.”

Mr. Zeidman said he planned to give some of the money to nonprofit groups, use part for a start-up business and spend some supporting a voter integrity project.

He does believe there was voter fraud in 2020. “The question is how much and was it actually enough to swing the election? I can’t say that,” Mr. Zeidman said.

He has joined the bipartisan political organization No Labels, he said, and won’t be supporting Mr. Trump for president in 2024.

“I’d rather see a presidential candidate who is not an extremist,” he said.