Beau makes a very important point, and I think it's one Biden and the Democrats should heed. The best way to attack Trump is to point out how weak he is. Not in an intellectual sense, nor in a moral sense. That falls on deaf ears in many quarters. Those of us who care about intelligence and well-structured arguments, about decency and compassion and moral consistency, already loathe him and would sooner vote for a rabid skunk.
The fact that he's a weakling, a coward, a whiner might gain some traction, though. He cowered in his bunker when the protesters got near the White House. He's failed to do so many of the things his supporters wanted him to do. He has even given up on denying the polls, his numbers, and on insisting how popular he "really" is. Now he whines that "nobody likes him," as if he were a petulant child. The fact that cares only about himself while people are dying isn't going to bother most of his supporters. They don't care about the people dying of Covid-19, or about Trump's being a narcissist or even a hypocrite. The fact that he is whining, though, might, bother some of them. Whining is for weaklings.
You can tell what bugs them about their own leader when they toss it back at the Democrats. When they try to say some Democrat or another is a whiner. When they make not-so-oblique comments about Biden hiding in a Bunker when Biden social distances, or they accuse those on the Left of being cowardly for wearing masks. It means they know their own leader is a coward at some deep, primal level, so the best they can do is cry, "You're another."
