one...going back to newt gingrich and the republican revolution...repubs want to nationalize the identity of the democratic party and define it by its most extreme elements. radicals, activists, nutbags, etc. this is why you see repub candidates in races across the country brand their dem opponent with being another liberal in a party that has gone too far left (even when the dem candidate is moderate or even conservative). its been very effective.

two...its to tarnish and kill her career in its infancy before she rises up the ranks and retains real power/influence and possibly starts winning senate/presidential/etc elections. basically the attacks dont even have to be substantive. just throw a bunch of shit at her to where she is constantly under a negative light and on the defensive (repub super pacs basically just do this the entire campaign season). and whenever she really does do something bad...youve already got confirmation bias in place to make past attacks look credible (the media has a history of abetting this behavior...either wittingly or unwittingly).

both of these approaches work well against a woman. and doubly well against a woman of color. even dems/liberals are liable to fall for some of it to some degree.