#US parties regularly had defections and replacements every 40 years or so going right up to when the bipartisan #Boomer alliance began passing laws to prevent that (1990s). Nancy Pelosi and Newt Gingrich were instrumental in that effort. 
Today, the kind of reforms you're suggesting (non-party elections) have been tried in a few states (Louisiana legislature, Ohio state supreme court, etc.) and led to more members of a single party rather than diverse membership, since there was no way to strategically reject unpopular candidates. Now the #Boomers are trying to push parliamentary systems as a way to let party bosses choose the winners instead. 
Proportional representation may look good in #CGPGrey 's YouTube video, but he's just bloviating against Britain's recent reforms to switch to a more-like-the-U.S.A. system. Maybe consider pushing along a different angle. Can you think of a workable alternative? 


