Wisconsin Governor and exploratory GOP presidential hopeful Scott Walker talks to the media after speaking at the Freedom Summit on May 9, 2015 in Greenville, South Carolina.National Journal

A controversial investigation into Scott Walker's fundraising could land at the Supreme Court—just in time for the Republican presidential primaries.

The justices are scheduled to discuss Thursday whether they should hear a lawsuit that involves the long, politically charged investigation into Walker's coordination with outside groups during his recall campaigns.

One of Walker's closest allies in the recall fight—the Wisconsin Club for Growth—is asking the high court to take the case. The group says it was unfairly targeted by an "intrusive, harassing, and damaging criminal investigation in retaliation for [its] First Amendment-protected advocacy."

The high court has already wrapped up oral argument for its current term. So if it does decide to take the Club's case, arguments and a decision would come sometime in the next term, which begins in October.

"If the Supreme Court takes it, I think it would probably take it because of the packaging of the case as prosecutors on a political witch hunt targeting conservatives," said Rick Hasen, a law professor at the University of California, Irvine, and the author of the Election Law Blog.

The lawsuit stems from an investigation into whether Walker's campaign illegally coordinated with independent political groups, including the Wisconsin Club for Growth, as he fought recall campaigns in 2011 and 2012. The recall efforts were spurred by Walker's aggressive moves to strip public-sector unions of their bargaining power—a campaign the state's Club for Growth strongly supported.

Prosecutors in Milwaukee County opened a secret investigation in 2012 into possible coordination between Walker's campaign and outside groups supporting him. The probe expanded to additional counties in 2013.

Prosecutors say the investigation was simply an inquiry into potential violations of state campaign-finance law. Documents from the investigation reportedly showed Walker's campaign aides encouraging supporters to donate to the Wisconsin Club for Growth during the recall campaign, saying the governor "wants all the issue advocacy efforts run thru one group to ensure correct messaging."

Wisconsin Club for Growth, however, describes the inquiry as a partisan crusade to intimidate Walker's allies and scare others away from donating to or working with them.

"Deprived of funds, cut off from its vendors and allies, and unsure even of what law it was alleged to have violated, the Club was paralyzed, as were all other major conservative advocacy groups in Wisconsin," it said in its brief urging the Supreme Court to take the case.

Hasen says those claims appear overstated, and that the case's political weight is greater than its ability to weaken laws against campaign coordination. "I see this case as having a lot of rhetorical and symbolic value, but I don't see it as, one way or the other, making major changes in campaign-finance law," he said.

Neither Walker nor his campaign are parties in the lawsuit, and an attorney for the prosecutors has said Walker himself was not a target of the investigation.

Wisconsin Club for Growth is challenging the investigation in both state and federal courts. The state Supreme Court is expected to rule this summer on whether the probe was on the up-and-up, and a federal appeals court said last year that the federal judiciary should stay out of the matter until then.

"Principles of equity, comity, and federalism counsel against a federal role here," a three-judge panel of the 7th U.S. Circuit Court of Appeals said.

The prosecutors who began the investigation also want the U.S. Supreme Court to hold off.

"Whether the "¦ proceedings are valid under Wisconsin law is a question unique to Wisconsin and it is through Wisconsin state courts that the question should first be resolved," they said in their brief urging the court to leave the 7th Circuit's ruling alone.

And there's certainly a chance the Supreme Court will decide to stay out of the issue—or to wait and see what comes out of the state Supreme Court. The justices were initially slated to discuss the case in early April, but have postponed their deliberations twice. And there's no way to know what those delays mean, Hasen said.

"I think there is a possibility that the Court takes it, though it could be that what the Wisconsin Supreme Court decides to do moots things," he said.

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