As expected, many on the left openly celebrated Trump’s illness, wishing upon him all manner of suffering and death. In general, though, the response of mainstream Democratic players was muted, even polite.

Why?

Perhaps because they know a sick person (even this president) engenders sympathy among decent people, many of whom are undecided voters. If contracting Covid suddenly reveals Trump as a vulnerable human being like the rest of us, he loses his primary value to Democrats — that of a bogeyman: a frightening, demonic creature, useful for dividing Republicans from Trump and driving Democrats to Biden.

And Democrats are nervous, because they need a bogeyman.