A large group of citizens, not traditionally engaged in political life but angry at a sitting President who does not face re-election, form a grassroots movement. As they gain power a young, relatively inexperienced politician becomes their spokesperson. The movement raises a ton of money, and consistently defeats establishment candidates from the party they are most closely aligned with. The movement has ill-defined policies, but is generally seen as more extreme than the party's traditional constituencies. By the time the party realizes it, the movement has eclipsed it, so all the party can do is come along for the ride, preferring some victory at the polls to defending its more traditional policies and actions.
The paragraph above describes the Tea Party and Sarah Palin. But it also describes Barack Obama and the movement that carried him to power. I do not mean to suggest equivalency between Obama and Palin. Nor do I believe that this is a case of history repeating itself. But it is part of a broad trend in civic life, where it is easier than ever to engage and connect with like-minded people to bring about short-term change. The case of Obama suggests that this sort of change may not be durable, but nonetheless we ought to realized that the Tea Party and the Obama revolution are part of the same thread in American life.