Republican Sen. Rob Cowles said he will vote for the state budget, lessening Democratic hopes to block the bill.
Cowles was one of the most vocal critics of the plan and had been working behind the scenes leading up to Thursday's debate to get changes. Republican Sen. Dale Schultz has been the loudest GOP critic and is widely expected to vote against the budget.
Republicans have an 18-15 majority. If more than one Republican opposes the plan, it will not have enough votes to pass given expected unanimous Democratic opposition.
Democrats on Thursday renewed their call for Republicans to join them in making changes to the budget that would cut income taxes for all brackets, expand private school vouchers statewide and reject a federally funded Medicaid expansion.