State Auditor Rebecca Otto on Thursday asked the Minnesota Supreme Court to reconsider a lower-court ruling that upheld a state law she believes limits the powers of her office.

The appeal would mark the third time the case has been heard. Two lower courts previously ruled against Otto, finding that a 2015 law allowing Minnesota counties to use private audit firms was constitutional. Otto has sued a handful of counties that have retained private auditors and contends that the law removes an essential public function of the state auditor.

In a statement Thursday, DFLer Otto said she maintains her argument and her commitment to support Minnesota's Constitution.

"I believe that, if left as is, the 2015 law will unacceptably diminish the protection this constitutional office provides the taxpayers of this state," she said.

The Court of Appeals ruled in May that auditing counties is an essential function of Otto's office, but that the law allowing counties to opt for outside help "does not disturb the state auditor's ultimate authority as the state's general accountant."

Much of the state auditor's budget has traditionally come from audit fees, but a change approved in the last legislative session shifted the entire budget to the state's general fund.

Rep. Sarah Anderson, R-Plymouth, backed the new law and has been critical of Otto's earlier challenges. She said Thursday that the latest appeal from Otto is a "waste of taxpayers' money" and doesn't match up with what many Minnesotans want. She noted that other government entities, including school boards and cities, are also permitted to retain private auditors.

"I don't know how many times she has to be told it was constitutional, what we did, and that it was the right thing to do," Anderson said.

Anderson was also critical of the cost of Otto's legal appeals of the law, which have so far totaled more than $250,000.

Otto, who was elected auditor in 2006, is a candidate for the DFL nomination for governor.

Erin Golden • 612-673-4790