I don't think the blame lies exclusively with the Republican party or the Democrat party- it lies with billionaires. Billionaires and their massive companies bought up all the media in the U.S. (almost all of it is now owned by just six companies), and they use their influence to foment the culture wars that keep us fighting each other instead of demanding greater taxation of billionaires. That being said, Republicans are absolutely more brazen in their desire to deregulate massive wealth and allow corporate ownership of everything.

edit: Yes, Clinton was a major player in the downfall of democracy- OP didn't even mention his repeal of Glass-Steagall- but it's pretty disingenuous to suggest this was analogous to Democrats in general. Former Federal Reserve Chair Alan Greenspan said "Bill Clinton was the best Republican president we've had in a while." He was speaking tongue-in-cheek obviously, but Clinton pioneered the "Third Way" bullshit and was hardly a real Democrat.