MADISON, Wis. (AP) -- A Republican-backed proposal giving tax credits to parents of students in private schools is being floated in the Legislature. The proposal comes as negotiations continue behind closed doors to find an alternative to Gov. Scott Walker's voucher school expansion plan. Republican Rep. Dean Kaufert says the bill he is co-sponsoring with Sen. Glenn Grothman could be a viable alternative to Walker's proposal which has hit a roadblock in the Senate. Walker's spokesman Cullen Werwie declined immediate comment on the bill. The tuition tax credit idea has been around for decades, but it's not gone anywhere in large part because of its high cost of more than $100 million annually. Voucher supporters say they are open to the idea, but not as a replacement to the voucher program.