It's weird, because literally no one was clamoring for Harris. It's not like she had a good run in the primary and just didn't cut it. She didn't even make it to a voting contest, right? I get that he wanted to check the gender and race boxes, but how about someone who wasn't already 100% rejected by the voters? Duckworth and Rice both would have fit that bill. Really struggling to figure this one out. Maybe duckworth disqualified herself with her moronic George Washington comments and he didn't want to deal with Benghazi all over again? After my initial disappointment, I'm still gonna vote for him, but c'mon Joe. You're really straining our anyone-but-Trump credulity.
The best explanation I've heard is that she was chosen to negate any "soft on crime" attacks the Republicans could make. Not that this actually stopped them from making them, but the hope may be to pull enough centrists his way.