This is partly why his ideas to fix it seem drastic - there really aren't any non drastic solutions that can work.
https://www.ted.com/talks/lawrence_lessig_we_the_people_and_...
It has nothing to do with which party is in power - the affect of fundraising has corrupted the underlying incentives of the entire congress.
I found his book on the topic pretty convincing: http://republic.lessig.org/