Two conservative groups are calling on the Wisconsin legislature to amend a law that currently could violate voters' rights to a secret ballot.

The Wisconsin Institute for Law & Liberty and the MacIver Institute released a report Wednesday arguing that a long-standing state election law conflicts with Wisconsin's constitutional guarantee of a secret ballot and should be repealed.

The groups contend that Wisconsin law requires election officials in municipalities that use centralized absentee ballot counting to write each voter's poll list number on the back of that person's absentee ballot.

Because both the poll list and completed ballots are public records, they argue the system could allow someone to determine how an individual voted.

"We have serious concerns that enforcing this statute at central count locations could violate voters' right to a 'secret ballot,'" WILL Associate Counsel Nathalie Burmeister said in a statement.

"We are hopeful the Legislature will amend the law and that WEC will work with local election officials to protect the right of all voters to have the way they voted kept private," added Burmeister.

MacIver Institute CEO Annette Olson said protecting ballot secrecy is essential to maintaining confidence in elections.

"Voter confidence in elections is critical in securing and preserving freedom in Wisconsin and America," Olson said. "Protecting the secret ballot should be everyone's priority."

According to WILL and MacIver, the law serves no meaningful election integrity purpose and instead creates the possibility that election officials or anyone accessing public records could match a voter to a completed absentee ballot.

The groups said such a system could expose voters to intimidation or coercion, even though they acknowledged there is no evidence the loophole has been exploited.

In an interview with The Federalist, Burmeister called the issue "a loophole" that lawmakers should resolve, arguing Wisconsin is one of only two states with a law that undermines statutory or constitutional ballot secrecy protections.

The groups are urging legislators to repeal the provision and direct the Wisconsin Elections Commission to ensure no voter-identifying information is transferred to counted ballots.

The renewed push comes a day after the Wisconsin Supreme Court ruled that guardianship records sought by a conservative election integrity group are not public records.

In a 5-2 decision, the court rejected an effort to obtain documents that could have been used to identify individuals deemed ineligible to vote because of incompetency, with the majority citing privacy concerns.

Conservative Justices Annette Ziegler and Rebecca Bradley dissented, arguing the records should have been subject to the state's open records law.

WILL and MacIver said the legislature has considered similar reforms during the past two sessions, but none have reached the governor's desk.

The groups argue fixing the ballot secrecy issue would strengthen election integrity while better protecting Wisconsin voters' constitutional rights.

The Associated Press contributed to this report.