COLUMBIA, S.C. - Gov. Mark Sanford's proposal to give tax credits to parents who send their children to private schools would take $354 million of out public schools, according to a report released by public school leaders on Tuesday.

The Miley and Associates report found that each school district on average would lose $4.1 million if the tax credit was fully implemented in five years.

Harry Miley, a former economic adviser to former Republican Govs. Carroll Campbell and David Beasley, prepared the report for the South Carolina School Boards Association and the South Carolina Association of School Administrators.

Miley took aim at last year's study released by the South Carolina Policy Council, a Columbia group that backs school tax credits. That report, produced by a Clemson professor, found that schools would have about $600 more per student when a child leaves a public school classroom for a private school.

Miley's report says the Policy Council study has several flaws. He said it didn't take into account the fixed costs that remain when a student leaves a classroom.

"I didn't think this quite passed the commonsense approach," Miley said. "Where are the cost savings? ... Is the teacher fired? ... Is the heat turned down?"

Ed McMullen, the Policy Council's chief executive, stood by Clemson economist Cotton Lindsay's report. It was "substantial, cutting edge data and research that is pioneering new ground" and is "highly regarded" nationally with economists, McMullen said.

Rather than just a few students, dozens of students will leave schools where they are unable to learn, Lindsay said. Those schools "will find their enrollments shrinking, and not by only five pupils per classroom, but by whole classrooms."

The governor has said the legislation would enhance school choice and create competition that would make public schools better.

Miley explains that public schools face different costs when students leave, which was not taken into account in the Policy Council's study. For instance, the Horry County School District gets $938 from the state Education Finance Act fund for each student, while the Hampton 2 School District gets $1,641, Miley said.

Lindsay said he is working on an updated report now that addresses those district-by-district concerns.

There also are differences within the student population, such as more may be spent on special needs and gifted students.

Instead of saving $600 every time a student leaves, the different needs of students may actually take between $570 and $2,040 out of schools, Miley's report says.

Miley said the questions raised by the report merit further study before the Legislature adopts a tax credit. "There are more questions unanswered than answered," he said.

The study validates what critics have been saying, said Porter Stewart, president of the school board group.

"The state cannot afford nor is it morally right to publicly fund two systems of education in South Carolina," Stewart said.

Lindsay said "it is not only affordable to do precisely that, but we can actually increase spending on public schools at no additional cost to the taxpayer."

McMullen said the study focuses on an outdated version of the tax credit proposal. "There is nothing reliable in what they've released," McMullen said.

Miley said the report's calculations include both the version that failed last year and what currently is before the Legislature.

The Republican governor's office stood by the tax credit plan, saying opponents include people that profit from the current bureaucracy.

"We've got a great deal for the current education bureaucracy," Sanford spokesman Will Folks said. "It can keep over two-thirds of the $9,800 it currently spends attempting to educate each individual child and we'll give parents access to the marketplace with the other third to make sure someone is actually educating that child," Folks said.

He said it was important to identify people looking out for the interests of children "as opposed to the bureaucracy that's padding its wallet."

Education Superintendent Inez Tenenbaum, a Democrat, said Miley's study makes sense. "I don't see how any reasonable, fair-minded person can continue to cite the Policy Council's so-called research as authoritative and unbiased." The council "continues to sacrifice truth and accuracy in the pursuit of its political agenda," she said.

McMullen said his group is not pushing a political agenda. "The person who has an agenda is Inez Tenenbaum," McMullen said.