American business is typically a reliable Republican cheerleader, but it is lukewarm about Senator John McCain's proposal to overhaul the healthcare system by revamping the tax treatment of health benefits, officials with leading trade groups say. The officials predicted in recent interviews that the McCain plan, which eliminates the exclusion of health benefits from income taxes, would accelerate the erosion of employer-sponsored health insurance and do little to reduce the number of uninsured from 45 million.