The Wisconsin governor, Scott Walker, has targeted only unions that have traditiionally supported Democrats — state employees, teachers — to lose collective bargaining rights. He has not gone after unions — police and fire, for example — that sometimes support Republican candidates.
UPDATE: Good commentary on Daily Kos about Walker's selective union busting:
The outlawing of independent unions is the clearest and most consistent marker of despotism around the world. When Gaddafi seized control of Libya in 1969, his first speech proclaimed the end of labor unions. No sooner had he secured control of Cuba than Fidel Castro banned the ability of unions to strike or to bargain over salary and benefits, saying such demands were detrimental to "the national economy." In Colombia today, right-wing militias work together with corporations to keep down costs and demands for decent working conditions in the most effective way they know—they execute union leaders.
There's a good reason why governments and corporations alike show trepidation when people are able to organize. Union is effective. For all the pretty speeches and all the ham-handed threats, the signal that the Iron Curtain was finally rising didn't come in Berlin or Washington, D.C., it came in the shipyards of Gdańsk, when men dared to wave the flag of an independent union. Want to determine where governments are actually concerned about the rights of their people? You only have to look at how free people are to organize for a cause. Without that, no other rights matter. With it, all other rights will follow.
PS — Walker created the budget "crisis" by passing a huge tax break the state couldn't afford. Sound familiar to Republicans at work in Arkansas?