Tea Party High, Tea Party Low
At the moment, it looks like the senate seat in Colorado is going to go Democratic. If it does, the tea party scorecard looks distinctly weak this cycle. In places like Utah, Kentucky, Florida, and Pennsylvania it produced victories that Republicans would have gotten anyway. In Delaware, Nevada, Colorado, and West Virginia, it produced losses where more mainstream candidates probably would have won. And in Alaska it produced a civil war.
In the House, though, the tea party seems to have done fine. So what to think of this? It seems like there are two obvious frames. The first is that insurgent movements like the tea party start out at the local level and move outward over time. So maybe it was too early for them to win statewide seats, but by 2012 they'll be in good shape. The second is that tea partiers can do well in local races where districts are fairly homogeneous and voter distress is easy to stoke, but that kind of angry entreaty just doesn't work at a higher level, which by definition requires a media-centric approach and a more pluralistic appeal.
I wouldn't bet the ranch on it, but I suspect the answer is more the latter than the former. As time passes, the economy improves (touch wood), and the tea party inevitably gets integrated into the machinery of the Republican Party, it's going to have to moderate its message to succeed. Just how much it's going to have to moderate is still an unanswered question.