The Legislature's nonpartisan budget office says the expansion of private school vouchers proposed by Republicans could cost as much as $800 million over the next decade.

The analysis was prepared at the request of Assembly Minority Leader Peter Barca, who released the memo publicly on Thursday.

Republicans voted last week to lift the enrollment cap on the statewide voucher program and let it grow in each district by 1 percent of total enrollment each year. They also changed the way vouchers are funded so that an increase in state aid to voucher schools would be offset by a corresponding cut to aid for public schools.

Barca said the memo from the Legislative Fiscal Bureau shows the long-term cost of that decision.

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"Now that is an eye-popping number. Up to $800 million will be diverted — stolen — from our public schools to go directly into the private voucher school experiment," said Barca.

Barca said the diverted funds could spell the beginning of the end of public education.

Jim Bender, president of pro-voucher group School Choice Wisconsin, discounted the estimate as "just a guess."