Biden couldn’t begin to campaign against Trump. No message, no enthusiasm. Can’t keep from groping women. Can’t remember what he’s doing nor relevant obvious facts.
Bernie is still enthusiastic, has an Overton-window-shifting message, doesn’t seem to offend (nay, he attracts) women, still has mental faculties intact. There’s just no hope of him keeping any of it up come 2021 or so.
Didn't he just have a heart attack? How old is he? I can't see these two facts helping him.