It’s easy to underestimate the tea-party achievement in ousting Senator Lugar. After all, haven’t the tea parties knocked off a lot of incumbent Republicans in primaries? Actually, no. Most tea-party successes have come in races for open seats. In the last Senate cycle, Specter was pushed out of the party before the tea parties even started, because he was unacceptable to a lot of types of Republicans. (Recall that he barely won his primary in 2004.) Bennett lost a convention, not a primary. Murkowski lost a primary, but came back in the general. Lugar is (if I’m recalling correctly–commenters?) the first Senate incumbent whose career has come to an end because tea partiers beat him in a primary. And he lost while having a reasonably conservative voting record: He had voted with pro-lifers, for example, unlike Specter and Murkowski.
You could tell a similar story in the House. In 2010, the only Republican incumbents to lose were Parker Griffiths–who had been a Republican for only a few weeks–and Bob Inglis, who had alienated conservatives over taxes, global warming, and national security. But a few weeks ago incumbent Jean Schmidt lost a primary almost purely on tea-party issues.
In short: The tea party may be losing popularity, but its power inside the Republican party appears to be growing.