The cloud that surrounds Scott Walker, the governor of Wisconsin and a would-be top-tier Republican presidential candidate, got a whole lot darker this afternoon.

Court documents unsealed Thursday showed that prosecutors allege that Walker was at the center of a “criminal scheme” to illegally coordinate with outside groups as he faced a fierce recall campaign in the middle of his first term.

According to the documents, Walker wrote to top Republican strategist Karl Rove laying out how his office was coordinating with the Club for Growth, and one of its chief advisers, R.J. Johnson, who is also an adviser to Walker.

“Bottom-line: R.J. helps keep in place a team that is wildly successful in Wisconsin. We are running 9 recall elections and it will be like 9 congressional markets in every market in the state [and Twin Cities],” Walker wrote to Rove.

Prosecutors allege that Johnson helped coordinate efforts among the Walker campaign, the conservative leaning Club for Growth, and other outside entities like the Republican Governors Association and Americans for Prosperity, a pro-business group backed by the wealthy industrialists Charles and David Koch.

Raising money and coordinating campaign activities with outside groups is a violation of a state law, and, according to prosecutors, “That coordination included a nationwide effort to raise undisclosed funds for an organization which then funded the activities of other organizations supporting or opposing candidates subject to recall.”

The revelations come as Walker finds himself in an increasingly tight reelection race against Mary Burke, a Trek bicycle executive and a former state secretary of commerce. A recent Marquette University poll had the race tied.

Democrats seized on the latest revelation.

“The documents released today raise more questions than answers about Scott Walker’s misconduct during his first term. Walker’s coordination with Karl Rove and a Koch-backed group, among others, is not only troubling and potentially illegal—it is a clear violation of the public’s trust,” said Michael Czin, spokesman for the Democratic National Committee. “For years, Walker has refused to answer questions about his conduct. Now that prosecutors have alleged criminal conduct by Walker, it’s time for him to come clean to the people of Wisconsin and face the consequences, whatever they may be.”

The documents became public as part of a lawsuit by the Wisconsin Club for Growth attempting to halt the investigation, known as a John Doe Inquiry, arguing that it is a violation of their free-speech rights. A federal judge last month sided with the organization, a fact that the Walker campaign seized on.

“The Friends of Scott Walker campaign are not party to the federal suit and have no control over any documents in that suit,” said Walker campaign spokeswoman Alleigh Marre. “Two judges have rejected the characterizations disclosed in those documents.”

Prosecutors, however, pushed back on the notion that the campaign activity was somehow protected by the First Amendment on free-speech grounds.

“No court has ever recognized that secret, coordinated activity resulting in ‘undisclosed’ contributions to candidates’ campaigns and used to circumvent campaign-finance laws is protected by the First Amendment. Accordingly, the purpose of this investigation is to ensure the integrity of the electoral process in Wisconsin,” they write.

Brendan Scholz, a Republican consultant in Wisconsin, said that he did not think the latest revelations were more proof of what local Republicans have long believed—that there is a coordinated effort by overzealous prosecutors to ensnare the governor.

“It is a headline in search of a crime to prove something that doesn’t actually exist. What really comes to light is the assault on these individuals associated with the conservative groups and the Walker campaign,” he said. “This certainly puts a stain on the prosecution and brings into question how big of a fishing expedition this actually was.”

And he predicted that Walker would ride out this latest wave in a saga that been going on for years now.

“I think this is part of the inside game that junkies make hay out of,” he said. “I don’t put this in the harm column for the future.”

Others weren’t so sanguine.

“Everybody is entitled to the presumption of innocence, and this is only the prosecutor’s side, but this looks very, very serious,” said Mordecai Lee, a professor of political science at the University of Wisconsin Milwaukee and a former state lawmaker.

He added that although Walker had weathered previous investigations into his campaign activities, “this is a different, because, if proven true, it shows personal involvement.”

“This could be the smoking gun,” he added.