To many it seems that idealism and partisan rancor in politics is at an all time high. While the latter may be true, the former is not. Over the last several decades, the two major political parties in the United States have loosened their ties to the traditional planks in their platforms and tightened their ties to lobbyists. There are many examples that show that each party is defined more by whether they are in power or not than any long-held beliefs. The most recent example is how politicians should behave in a time of war. A few years ago, Democrats freely criticized the President's handling of the War on Terror. The Republicans were quick to denounce such criticism as unpatriotic and dangerous. With a new President, the roles have quickly reversed.
Similarly, a few years ago the Republicans decried the use of the filibuster while the Democrats defended it. Now, with the current Republican minority breaking a record for filibusters, the roles are reversed. The same holds true for the President's judicial appointments, Medicare expansion, deficit spending, Wall Street bailouts, the farm bill, etc.
Aside from the social issues that the parties use as a wedge but never actually do anything about, there is really not much that either party stands for now; nor much of substance that differentiates them from each other. Rather, each party happily does the bidding of their lobbyist overlords, each framing the gifts as something that has always been at core of their party's platform.