A federal judge Friday shot down a wide-ranging challenge to Minnesota's voting system.

U.S. District Court Judge Donovan Frank dismissed a case filed by the Minnesota Voters Alliance, state Rep. Sondra Erickson, R-Princeton, the Minnesota Freedom Council and others, according to a copy of Frank's order supplied by Secretary of State Mark Ritchie.

Ritchie, who was a defendant in the lawsuit, issued a statement saying Frank "affirmed the constitutionality of same-day voter registration," which Ritchie said "serves as a model for our nation and, in part, accounts for our consistent top ranking in voter participation."

Frank said in his order that those filing the lawsuit "failed to state a claim against Defendants upon which relief may be granted." In addition to Ritchie, defendants included Attorney General Lori Swanson, Ramsey County and Crow Wing County elections officers.

Erick Kaardal, attorney for the Minnesota Voters Alliance and other plaintiffs, said he will file an immediate appeal and still has hopes of prevailing before the Nov. 6 general election.

The lawsuit made several charges against the voting system. It claimed elections officials did not confirm the eligibility of those registering on election day before those votes were counted. It said Crow Wing County allowed people with disabilities who are under court-ordered guardianship to vote. It claimed "ineligible persons had their ballots counted" due to election-day registration and called for a permanent injunction preventing the government from counting the votes of election-day registrants until "they are confirmed as eligible voters."

Frank said those filing the suit "cannot establish that Defendants violated any constitutionally protected right." He said to establish such a constitutional violation, "election officials must have engaged in invidious discrimination or intentional misconduct," which the plaintiffs did not claim.

As to confirming voters eligibility, Frank wrote that the claim is "based on the erroneous premise that elections official must verify voters' eligibility before their votes are counted. Under Minnesota election statutes, voters themselves certify their eligibility to vote, under threat of criminal prosecution if they do so falsely."

The judge also said people with disabilities who are under legal guardianship do not automatically lose their rights to vote. "Persons under guardianship are presumed to retain the right to vote unless otherwise ordered by a court," he wrote.