Harris will energize and capture the black vote more than any other candidate - because she is a black woman.
Harris will energize progressive, liberal and many moderate women voters - because she is a woman.
Harris will get the progressive, liberal men's vote.
Harris is a formidable debater and is very capable of throwing effective bombs at her opponents, as Biden is experiencing.
Our anti-Christian, anti-Conservative, anti-American: news, social media and educational institutions will canonize Harris and crucify President Trump. This will be true regardless of who the democrat candidate is but again - this is one more thing that could propel Harris to the presidency.
I think this ticket would be aimed at getting black votes and gay (and gay-corporate) cash.