MADISON, Wis.—Even after a wave of Republican victories in this month’s elections, targets of a Milwaukee County district attorney’s investigation say the probe effectively chilled conservative donors and volunteers.

Critics say the Democrat district attorney’s investigation, launched in 2012, was aimed at disrupting the campaigns of Gov. Scott Walker and other state Republicans.

“We spent, but we didn’t spend like we did in the last couple of cycles, and I believe a good part of that was related to the John Doe investigation,” one source, whose organization has been targeted in the probe and is still afraid to speak out, said this week.

Another target of the investigation, launched by Milwaukee County District Attorney John Chisholm, said some donors took a pass this election cycle but that it is difficult to calculate the impact on spending.

“Our side had what it needed, and outside of the governor’s race, the left had very few players on the field,” said the source, who also asked not to be identified for fear of reprisal.

The conservative Citizens for Responsible Government took the unusual step of asking a federal judge in October for permission to discuss policy issues with elected officials or candidates without the threat of a lengthy and invasive criminal investigation.

“We work cooperatively, not illegally, with like-minded groups. When their sources shut off, some of our sources shut off,” an activist said. “I think you can attribute the drop-off to the chilling effect of John Doe.”

Conservatives say a Democrat district attorney's investigation attempted to silence them. (Photo: Getty Images)

Conservatives say a Democrat district attorney’s investigation attempted to silence them. (Photo: Getty Images)

Eric O’Keefe, director of the Wisconsin Club for Growth, is the only John Doe target who has defied the gag order and spoke publicly.

O’Keefe and the club have sued Chisholm, two of his assistant DAs, John Doe special prosecutor Francis Schmitz, and Dean Nickel, an investigator contracted by the state Government Accountability Board, alleging the prosecutors grossly violated the conservatives’ civil rights—chief among them, their First Amendment right of speech.

The Wisconsin Club for Growth, active in issue advocacy during previous election cycles, spent nothing on issues ads in 2014, O’Keefe said this week. The organization continued to publish its e-letter and did some advertising on Right Wisconsin, an online conservative news source, but that was it.

“It is not clear yet whether we should ever resume issue advertising, as our brand has been redefined by the John Doe propaganda that calls in question its likely effectiveness as a voice of persuasion,” O’Keefe said.

Chisholm and his fellow prosecutors have repeatedly declined to comment, or have not returned requests for comment.

Read more at Watchdog.org.