(Hamilton Co.) A proposal to raise the county sales tax to 6-point-75 percent is on the table backed by Hamilton County Commissioner Todd Portune. He says it's to raise revenue to support unfunded expenses for the two Riverfront stadiums. Comissioner Greg Hartman says he's considering the idea. Both say they would only back the plan if the Bengals and Reds contribute more to the fund.  A majority of the three-seat board is needed to pass the tax hike. Right now point-5 percent of the county sales tax goes into the stadium fund. This plan would increase that to point-75 percent. Last year, the Commsioners sold the county's rehabilitation hospital to cover the fund's deficit. Portune says raising the county sales tax would solve the shortfall problem permanently.