Democrats, welcome to your very own tea-party problem

It seems safe to say that Sen. Elizabeth Warren (D-Mass.) sincerely wants to see every American covered by a single-payer public health-insurance program. After all, she’s been saying as much since long before she ran for office. Her fellow candidates are also undoubtedly earnest in their desire to expand health-care coverage one way or another. Yet it also seems safe to say that most of them would rather be talking about something else. Health-care policy is all about detail, and few of them have bothered to muster any command of...