As more polls show that Hillary Clinton could lose to Donald Trump, Democratic media and political elites have decided that the problem is—Bernie Sanders. The socialist warhorse has had his campaign fun, but now he and his supporters refuse to slink away quietly into Howard Dean obscurity. Doesn’t he know that his persistence is helping Republicans?

We’d humbly suggest that these Democrats are looking through the wrong end of the campaign telescope. Bernie’s continuing string of victories is the symptom of the political demand...