Kamala Harris seems to be the 2020 candidate that the rich Clinton backers are getting behind. So here is some background on her:

As California Attorney General, she was the champion of an extremely punitive truancy law (which mostly affects black and Latino youths). She supported the death penalty. She laughed at marijuana legalization. She supported using prisoners as slave labor. And yet she was not-so-tough on crime when it came to corporate criminals like Steven Mnuchin, now Trump's Treasury Secretary.

As a Senator, she's offered tepid, caveat-laden support for Single Payer ("as a concept, I'm completely in support of single payer, but we've got to work out the details, and the details matter on that."). She mainly seems to have come to prominence for her performance in the Russian Show Trials.