Walter Russell Mead, writing at the American Interest, has a diagnosis that I pass along because it is provocative but not necessarily because I entirely endorse it:
Our political system is in deep trouble, and while one can think of some procedural fixes that could help (superdelegates on the Republican side, stronger and more impartial enforcement of government rules on information security and conflict of interest in the case of the Clinton machine) the real problems are more dangerous and harder to treat: A moral and spiritual collapse that has frayed the bonds between the country's ordinary people and those who seek to lead them, a hollowing out of institutions from Congress and political parties to local churches and civic life, and the disintegration of a shared national intellectual and cultural framework for discussing the issues that confront us. As we approach a critical presidential election at a time of global turmoil and disorder, the state of our union is not strong.