Massachusetts businesses have joined with most of the state's health insurers in a new lobbying group called the Coalition for Affordable Health Care. The group is aimed at controlling healthcare costs and preventing more universal-coverage expenses from being shifted to employers. Representatives from the Coalition said it will fight efforts to increase assessments on employers who do not provide health coverage for workers. It will also oppose raising the standards for what constitutes a "reasonable" contribution under the state's healthcare overhaul law.