Yes, Pelosi, It's Hard

To understand why the Rangel scandals are so dangerous for Democrats, you need to understand something about midterm landslides: They’re usually composed of three parts. First, the other party’s activists are highly motivated. Second, your own activists are highly unmotivated. Third, independents want to burn Washington to the ground.

...In Washington, congressmen violate ethics rules all the time. But when independents get in one of their sour moods, these infractions become matches on dry tinder.