The second alternative is to strengthen private insurance markets, so that they’re covering more people and holding costs. Yet the Trump administration and many other Republicans — both governors and members of Congress — are now doing the opposite. They’re sabotaging the private insurance markets created by Obamacare. If those markets fail, it will leave many Americans who don’t get insurance through their job without coverage.

The weaker private markets become, the more political momentum government-provided insurance will have. Some Democrats will push for a gradual expansion of Medicaid and Medicare. Others, like Sanders and his growing list of allies, will push for an entirely new system. I don’t expect them to succeed anytime soon, but the debate over health care has moved much further to the left in recent years than I expected to see. And the Republican Party is largely responsible.

Elsewhere, Paul Waldman and Jonathan Cohn explain that the Sanders plan is more a conversation starter than a finely honed proposal. A big reason is that Sanders still hasn’t talked much about the hard choices and tradeoffs involved. But he did get more specific yesterday about the potential ways to pay for the plan, including a broad tax increase on workers (dressed up as a tax increase on businesses) and a range of tax increases on the wealthy. My favorite: Create a new top income bracket, on income above $10 million a year.

In Politico, Bill Scher argues that the Sanders plan will ultimately hurt Democrats: They will overpromise and disappoint their base, sacrifice other priorities and squander their recent political victory on health care. In The Times, Margot Sanger-Katz offers her take on the Sanders plan, writing that his changes to Medicare “are intended to make the health care system more affordable, but the details could have big effects on what sorts of care might be developed and made available.”