In the United States, politics is played in part by cooperation and building the coalitions needed to secure votes, but much of it is also adversarial partisanship, especially in the legislatures and the media. This leads to a question what is appropriate behavior and what is out of bounds (besides that which is explicitly illegal or unconstitutional)?
Since Obama's inauguration, for example, Republicans, especially in the Senate, have followed the strategy of opposing Obama's agenda vociferously, using procedural tactics like the filibuster and outright lies (e.g., "death panels") in the popular media (compare this with Democrats' approach following 9/11). It may be said that they have frustrated the will of the majority who voted for Obama and Democrats to Congress in 2008. However, the Republicans' tact gains them points with conservatives and Republican loyalists while eroding popular trust in Obama and the Democratic-controlled Congress by making them look unable to govern effectively (oh, and scaring them about "socialism").
This is hardly to paint Democrats as innocent. Recent scandals among Democratic governors and legislators is proof enough of that, but I think these kinds of ethical lapses are more clearcut examples of personal misconduct and/or abuse of power. What I am talking about here, though, is the ethics of campaigning and legislating. Is a highly Machiavellian approach unethical? Or is it just part of the game of politics?