Amendment 5, a November ballot initiative that could cut property taxes by a statewide average of 25 percent and increase the sales tax from 6 percent to 7 percent, may face obstacles from small businesses. The plan is expected to create a $4 billion budget gap. John Sebree of the Florida Realtors Association, which has pledged $1 million to support Amendment 5, said small business opposition may come from the lack of immediate effect. The measure would eliminate property taxes as a source of funding for public schools. A Palm Beach Post investigation in March posited that the amendment would mean a tax increase for that state’s poorest residents, who spend a larger proportion of their income on sales taxes and less on property taxes, while providing a break for its richest.