Republican lawmakers in Wisconsin have reversed half-a-century’s middle-class progress in the state by erasing collective-bargaining rights for public employees. Union members, caught off guard and infuriated by the Senate vote on Wednesday and the Assembly vote on Thursday, immediately talked of legal challenges and general strikes, but the outcome was probably inevitable given the Republican success in the 2010 elections. Now union members have to make sure they do not stay away from the polls again when their rights are at stake.

The vote, pushed by Gov. Scott Walker, would have happened weeks ago if Democratic state senators had not fled to Illinois to deprive the Senate of the supermajority it needs to pass bills that are considered fiscal matters. Republicans then moved the bargaining rights from a larger budget bill to a separate bill that they could pass by proclaiming that the rights were not a fiscal issue.

And, in doing so, they reluctantly exposed the real truth behind the maneuver: stripping the unions of their rights was never about the budget, especially once the unions had agreed to significant concessions on pensions and health care. It was always about politics. Governor Walker had hoped to hide behind a cooked-up budget crisis, but the fleeing Democrats at least succeeded in pulling away that facade.

Undermining public unions — and the support they give to Democrats — has been a long-sought goal of the Republican Party and many of its corporate backers. Koch Industries, one of the party’s biggest supporters, spent $1.2 million last year to help elect Mr. Walker and other Republican governors who want to eliminate or reduce bargaining rights. On Wednesday, the State Senate’s Republican leader, Scott Fitzgerald, told Fox News that if unions lose the battle for their rights, they would have less money to help President Obama win re-election.

Some union benefits are exorbitant, but no politician was forced to hand them out. Lawmakers are free to end this practice and should, but ending the basic rights of unions is a very different matter. It could have serious consequences for the Wisconsin Republicans who voted to do so. Recall efforts against Mr. Walker and several Republican senators are already under way. Polls in The Times and The Wall Street Journal have consistently shown large national majorities against these kinds of union-busting moves.

More broadly, the overreach by Mr. Walker and Republicans elsewhere has finally revealed their true agenda to blue-collar voters who either voted for them last year or who stayed home. These voters are not going to benefit from a crippled union movement; they live next door to the teachers and nurses and D.M.V. clerks who are about to lose what little clout they had in the state capital. Many have suffered during the recession and have watched in pain as private-sector unions have been battered to the point of ineffectiveness.

They understand the power play that took place this week. The place to exercise some power of their own is at the voting booth.