Let’s be clear about what this would mean. According to the most recent government statistics, more than 218 million Americans now participate in private health-care plans, of which 179 million are employment-based. As critics of Medicare for All have pointed out, many of these plans are the result of tough negotiations in which employees have compromised on wages and working conditions in return for more-generous health-insurance benefits. These workers would be asked to surrender their hard-won gains in return for a promise that they will prefer what they get from the government instead.

In the early 1960s, when I was young and 70% of Americans told pollsters they trusted the federal government, this promise might have garnered wide acceptance. Today, with trust below 20%, it will be a much harder sell.

Don’t take my word for it. As recently as March 2018, according to the Kaiser Family Foundation, support for Medicare for All stood at 59% and opposition at just 38%. Now, after more than a year of intensifying discussion, support has fallen 8 points, to 51%, while opposition has risen by 9 points, to 47%.

Here’s a big reason why. As recently as January, 67% of those who favored Medicare for All believed that it wouldn’t jeopardize their family’s current health insurance. Although Kaiser hasn’t updated this figure, many of the plan’s early backers must have discovered that their prior belief was contrary to fact.