I'd say you -- mind you, I'm writing from the other side of the Atlantic, and even if I have lived in the US, that was a long time ago! -- have lunatic right-wingers in power and lunatic liberals who think they are entitled to running the show as the (weak but noisy) opposition.
Why does this happen? Because close to nobody votes in the primaries, and so it is mostly candidates who have rather extremist views that are chosen by the two parties. How to solve this? By getting more people to vote in the primaries, so that more middle-of-the-road candidates are chosen.
How would this be even possible? Only if expressing one's vote were much simpler. I pretty much subscribe to Bradley Tusk's view (see: Vote with your phone: Why Mobile Voting Is Our Final Shot at Saving Democracy) that allowing people to vote from their phones is the only way to save the US.