See this decision in Hatchett v. Barland. I think if the government chooses to appeal this ruling to the 7th Circuit, it it has a pretty good chance of obtaining a reversal.
Here is the text of an email I received from the James Madison Center on the case:
Federal District Court Rules Wisconsin Campaign Finance Law is UnconstitutionalFor the second time in as many years, a federal judge in Wisconsin has ruled that a Wisconsin campaign finance law is unconstitutional. On September 14, the court ruled that Charles G. Hatchett, a resident of Whitewater, cannot be made to register with the state and include a disclaimer on post cards and flyers urging his fellow residents to vote against a referendum. Mr. Hatchett filed suit in March, 2010, arguing that these laws violate his First Amendment right to free speech.James Bopp, Jr., an attorney representing Mr. Hatchett, states: “this is the second time these overreaching campaign finance laws have been ruled unconstitutional in situations like this. It’s encouraging to see the federal court affirm, once again, that individuals in Wisconsin can send a post card concerning a referendum in their own town without registering and filing reports with the state.”The case is titled Hatchett v. Barland. Mr. Hatchett won a preliminary injunction in April, 2010, allowing him to immediately undertake his activities without complying with the challenged laws, and now the court has ruled those laws are unconstitutional in situations such as Mr. Hatchett’s.