Walker's recall campaign and other conservative groups have been investigated since 2012 as part of the secret probe, known as a John Doe. The investigation focused on alleged illegal campaign fundraising, spending and coordination between conservative groups, Walker's campaign and others during recall elections in both 2011 and 2012.
A person close to the investigation told The Associated Press on Wednesday that lead investigator Francis Schmitz is talking with Walker about a possible settlement that would end the probe.
That news set off a flurry of activity from Wisconsin Club for Growth, which filed a lawsuit challenging the investigation, and Schmitz. Earlier this month U.S. District Judge Rudolph Randa sided with the conservative advocacy group, saying the probe violated its free speech rights. The judge granted a preliminary injunction halting the probe.
Prosecutors have appealed the issuing of the preliminary injunction and asked the 7th U.S. Circuit Court of Appeals to put it on hold.
Walker's campaign is not a party to that lawsuit but has been a target of the investigation. Walker's campaign released an unsigned statement Thursday that did not address the status of any possible settlement of the investigation, but instead reiterated that Walker is not a part of the Wisconsin Club for Growth lawsuit.
Wisconsin Club for Growth lead attorney David Rivkin on Wednesday sent Schmitz a letter warning him that discussions with Walker to settle the investigation could be a violation of the judge's order.
Schmitz late Wednesday filed a request with the judge to clarify the scope of the preliminary injunction, asking if it affects his conversations with attorneys of those targeted.
Wisconsin Club for Growth filed an objection to that request on Thursday, saying Schmitz needs to provide more information about what he is doing and what he wants to do that risk violating the injunction.
It appears that Schmitz is trying to find a way around the court's order halting the investigation, Rivkin wrote in the motion.
Rivkin, in a letter to Schmitz's attorney on Wednesday, expressed concern that any settlement talks that would violate the "speech or associational rights" of Wisconsin Club for Growth or O'Keefe would be a "blatant violation of the preliminary injunction."
Schmitz's attorney Randall Crocker said that Schmitz has done nothing to violate the judge's order as he understood it.