Speaking on NBC's "Meet the Press," Walker said, "If we do not get these changes, and the (state) Senate Democrats don't come back, we're going to be forced to make up the savings in layoffs, and that to me is just unacceptable."
Democratic state senators have left the state to prevent a vote on Walker's measures.
Even though union leaders have offered concessions on pensions and health insurance, Walker said, "Over the past two weeks, even after they've made those promises, we've seen local union after local union rush to their school boards, their city councils ... and rush through contracts that had no contribution to the pensions and no contribution to healthcare."
He also said collective bargaining lets unions arrange deals like getting their health insurance from a teachers union-owned company, which Walker said costs $68 million more than the state-run plan.
"As a former local government official, I know that collective bargaining has a cost," he said.
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