A nonprofit group and three Georgia voters are challenging the results of the lieutenant governor's election, arguing that there might have been tens of thousands of votes never recorded in the race.

The Coalition for Good Governance alleges that an accurate result in the Nov. 6 election can't be determined because of flaws and malfunctions in the electronic voting system, according to a lawsuit filed Friday in Fulton County Superior Court.

The conduct of the election "was so defective and marred by material irregularities as to place in doubt the result of the election under Georgia law. This court should therefore declare the contested election invalid and set the date for a second election between the same candidates," the lawsuit states.

It said the large difference in votes for all other statewide races and the low reported participation rate in the lieutenant governor's race also are factors in the lawsuit, which names Secretary of State Robyn Crittenden and the election boards of Fulton, Gwinnett and DeKalb counties as defendants. Crittenden's office did not immediately respond to a request for comment.

The declared winner was Geoff Duncan, who had 1,951,738 votes to Sarah Riggs Amico's 1,828,566.

The suit seeks a new election for the office and asks that it be conducted on paper ballots read by optical scanners.

"Citizens must not permit flawed elections to stand," said Bruce Brown, an Atlanta-based attorney representing the plaintiffs. "Otherwise our democratic process fails. Until Georgia election officials commit to conduct fair and verifiable elections, the courts must intervene on behalf of Georgia voters. We look forward to a prompt resolution to this case and a new election conducted in a responsible and legal manner."

The lawsuit notes that the lieutenant governor's race reported only 3,780,034 votes, while every other statewide race tally exceeded 3.843 million votes. The plaintiffs allege that "this high under-vote rate is a likely result of the touchscreen voting system malfunctions, and that the un-auditable system does not permit a reliable determination of the vote count."

Georgia's election practices have been challenged repeatedly in court this year.

Democrat Stacey Abrams, who ran for governor, has promised to file a federal lawsuit over the way Georgia elections are run. She accused Brian Kemp, the state's governor-elect, of using his office as secretary of state to aggressively purge the rolls of inactive voters, enforce an "exact match" policy for checking voters' identities that left thousands of registrations in limbo, and enact other policies to tilt the outcome in his favor.

The claims in the election contest filed Friday reflect many of the issues raised in the Curling v. Kemp lawsuit regarding Georgia's flawed electronic voting system. The Coalition for Good Governance also organized that 2017 lawsuit now pending in federal court. The secretary of state's office and the State Election Board have appealed the case, which is expected to be tried next year.

"Georgia voters must not be forced to accept election outcomes that cannot be verified and in which they have no confidence. The anomalies in this race, combined with the thousands of voters' complaints of malfunctioning machines, erroneous voter registration files, improperly rejected ballots, and irregularities in vote counts, cast tremendous doubt on the election," said Marilyn Marks, the executive director of the Coalition for Good Governance.

"Every Georgia voter deserves to have confidence her vote is counted as cast," said Morgan County voter and plaintiff Jeanne Dufort. "Our secretary of state and election officials are supposed to guard that trust – instead, the people of Georgia have had to rely on the courts to make sure our elections are fair and secure. We demand better. It's time for voter-verified paper trails with post-election audits and secure, accurate voter rolls."