A vast majority — 70 percent — of Americans in a new poll supports "Medicare for all," also known as a single-payer health-care system. The Reuters–Ipsos survey found 85 percent of Democrats said they support the policy along with 52 percent of Republicans. Medicare for all has been in the headlines after a study by the libertarian-leaning Mercatus Center at George Mason University found it would lead to $32.6 trillion increase in federal spending over a 10-year period. The study’s author, Charles Blahous, wrote in The Wall Street Journal earlier this month that even doubling taxes would not cover the...