By SCOTT BAUER Associated Press

MADISON — Oral arguments in the appeal of a federal judge's ruling halting an investigation into Gov. Scott Walker's recall campaign and other conservative groups have been set for Sept. 9, exactly two months before the Republican stands for re-election.

The 7th U.S. Circuit Court of Appeals in Chicago set the argument date late Tuesday. The court also will hear arguments over a media coalition's request that all records in the case be made public.

No charges have been filed against Walker or anyone else as a result of the investigation, which began in secret in 2012 but has since been largely revealed through court filings and other public statements.

Prosecutors have said in court filings that they are looking into allegations of illegal campaign activity involving Walker's campaign, Wisconsin Club for Growth, the state chamber of commerce and conservative groups during the 2011 and 2012 recalls.

Special prosecutor Francis Schmitz described what he called a "criminal scheme" by Walker to evade campaign fundraising and coordination laws, according to a document written in December but made public in June. An attorney for Schmitz subsequently said Walker was not a target of the probe and that document laid out a legal theory, but that no determination had been made to bring any charges.

Walker, a potential 2016 candidate for president, has said repeatedly he did nothing wrong and that his political opponents, including Democratic challenger Mary Burke, are slandering him by referring to his involvement in an alleged "criminal scheme."

Under Wisconsin law, third-party political groups are allowed to work together on campaign activity, but barred from coordinating that work with actual candidates. The Wisconsin Club for Growth has argued the prohibition does not apply to it because it does not specifically tell people how to vote or run ads with phrases like "vote for" a certain candidate.

U.S. District Judge Rudolph Randa, in his May ruling halting the investigation, agreed with that argument and found that the probe was a violation of the group's free speech rights.

The state court judge overseeing the probe, known as a John Doe, quashed prosecutors' requests for subpoenas in January, also effectively halting the investigation.

David Rivkin, attorney for Wisconsin Club for Growth, said Wednesday he was pleased with the date being set. An attorney for prosecutors, Sam Leib, did not immediately return a message seeking comment.

Prosecutors faced a Friday deadline to submit briefs to the court, with Wisconsin Club for Growth having until Sept. 2.

On Monday, Randa also rejected Wisconsin Club for Growth's request to add the director and six members of the state's elections board as defendants to the lawsuit, saying he couldn't do that while the appeal was pending.