That belief would prove naive. The choices Shumlin favored would essentially have doubled Vermont’s budget, raising state income taxes by up to 9.5 percent and placing an 11.5 percent payroll tax on all employers — a burden Shumlin said would pose “a risk of economic shock” — even though Vermonters would no longer pay for private health plans. Far and away the biggest hurdles, though, were untamed health-care costs, which were growing faster than the U.S. economy and making care increasingly unaffordable no matter how it was paid for. “What I learned the hard way,” Shumlin said, “is it isn’t just about reforming the broken payment system. Public financing will not work until you get costs under control.”