Bloomberg is a gift to Sanders

To grasp how much Bloomberg’s participation in the debate helped Sanders, imagine what would have happened had the DNC not let Bloomberg in. In all likelihood, Buttigieg, Klobuchar, Biden—and perhaps even Warren—would have focused more of their wrath on Sanders. And it might have worked because Sanders this week made a mistake that left him vulnerable.

Last November, after Sanders suffered a heart attack, ABC News and The Washington Post asked Democratic-leaning voters which candidates were healthy enough to be president. Eighty percent answered Elizabeth Warren was. Seventy-four percent said Joe Biden was. For Bernie Sanders, the figure was 48 percent. Since then, Sanders has largely evaded this political liability. But it returned this week when he told a CNN Town Hall that he wouldn’t release his medical records, and a campaign spokesperson likened the issue to birtherism.

Sanders’s health is a legitimate issue for voters to consider. And he has no good answer for why he won’t release his medical records. Had his opponents pressed the subject as forcefully as they pressed Bloomberg on stop-and-frisk and mistreatment of women, they could have made that vulnerability the story of the night. They didn’t.