Looks like Klobuchar's chances of getting the VP spot may have dropped. Apparently she
chose not to prosecute the Police Officer who murdered Floyd in a previous excessive force citation while she was the county attorney. Whether or not that action was justified, it will definitely cause Biden to lose votes if he picks her.
Lose votes from whom, though?
Because of the way votes are allocated by the EC, a lot of votes for president are actually redundant. Biden could lose a lot of votes in some blue states, and it wouldn't change the outcome at all. On the other hand, losing a few votes in a few swing states could change everything.
The question when picking a VP isn't, "will I gain or lose votes?" The question is, "which votes will I gain, which will I lose, and which do I need to win?"
Also, every potential pick is going to have dirt on them somewhere. It's not hard to dig it up. The real concern is whether or not the media decides to make something of it, and whether people actually decide to care. If Biden picks Klobuchar, and the media doesn't start blasting the message that she's a bad pick and Biden is a bad candidate for this reason, then it won't matter.
I almost wish he would pick Klobuchar, just to see what would happen. Would Fox News run with the above story? Would their audience overlap with the votes Biden needs, enough for it to matter?
Which PACs would run campaign ads about it? I guess that's probably the real concern: Biden picks Klobuchar, and right-wing PACs start running attack ads on this point in states where Biden needs to keep or gain votes.
So the goal is to pick a candidate whose unavoidable dirt isn't the kind of thing that turns to mud and sticks in swing states (or whatever demographic Biden needs his VP to pick up votes with*).