Andrew Gelman isn't surprised that the Tea Party has lost its punch in Washington:
[W]hat it takes to mobilize voters in an election is not the same as what it takes to win votes in Congress, or even what it takes to scare members of Congress into thinking they might lose the next election.
To put it another way, the Tea Party voters did their job, just as the Obama voters did their job two years earlier. They expressed their preferences and changed the government. Now it’s the politicians turn to do their jobs, which is not to follow the wishes of their more extreme supporters, but to govern in a way such as to earn majority support in two years.