Seventy-two percent of large employers think Medicare for All will decrease the number of uninsured in the U.S., and 55% are in favor of expanding Medicare to people ages 50-64.

However, most of the 147 companies surveyed by the National Business Group on Health (NBGH) think moving to a Medicare for All system covering everyone under the government program will increase health-care costs, dampen innovation in health-care delivery, and hurt quality. Forty percent think Medicare for All will decrease access to health care.

The findings reflect the mixed feelings many employers have about the proposal touted by some...