McCabe predicts that Walker and the four GOP senators likely to face recall elections will enjoy a sizable money advantage. Some $60 million or more is expected to be spent, according to reports.

McCabe says Walker has a huge advantage because he is currently raising unlimited amounts of money due to a legal quirk that removes limits because he is the target of a recall. Walker had raised more than $12 million by mid-January, and absent a candidate with the personal wealth of Democratic U.S. Sen. Herb Kohl, who has said he has no plans to run, Walker is likely to have a big edge, McCabe says.

McCabe points out that the 12-to-1 ratio was estimated before the attack on collective bargaining rights. "It will be much harder now for public sector unions to exist," he says. "Unions are in a tougher financial position."

Adds McCabe: "Unions were already losing badly. For corporate interests to say that this election is all about big union bosses, that is a very large pot calling a much smaller kettle black. It really is."

For historical context, I spoke with William Powell Jones, a University of Wisconsin-Madison history professor and an expert on public sector unions in modern times.