Remember that Nancy Pelosi’s strategy for winning a House majority in 2006 was to recruit conservative Democrats to run in right-leaning districts. On the campaign trail, they would sound like they shared the values of their constituents, but once in DC they would be reliable votes for Pelosi, Barney Frank, and the rest of the far-left Democratic leadership. This meant that there were a lot of districts represented by “Nancy Pelosi Democrats,” whose constituents were future Tea Party sympathizers. Once the Tea Party movement activated these voters and got them engaged in the election, it swept dozens of Democrats out of office.
Take Charlottesville. It may be a left-leaning university town, but it’s part of Virginia’s fifth congressional district, which includes Lynchburg (home to a very different university founded by Jerry Falwell) and large swathes of Virginia’s rural Southside, so the district as a whole is much more conservative. In 2008, Democrat Tom Perriello defeated the Republican incumbent by about 800 votes, in the best election year for Democrats in a generation. He was unlikely to keep that margin and was duly booted out in 2010.
Once that was finished, many Tea Partiers could reasonably conclude that, when it came to national politics, they had done their bit. They had fired the folks who voted for bailouts and runaway spending and ObamaCare and put in new representatives who promised to oppose all of these things. So we shouldn’t be surprised that the movement lost some of its momentum. It lost momentum by winning.