I think you meant to say that the Tea Party wasn't the force in 2012, that it was in 2010.
I won't dispute that observation, but I will comment that I believe the true drop in Tea Party enthusiasm coincided with the general realization that our side was not going to get behind our most dedicated and courageous champion, Sarah Palin, and that for whatever reason, she also decided that 2012 wasn't her 'moment'.
This was an enormous blow to the momentum we all saw in 2010, and should not be discounted.
That isn't to say that Sarah Palin is supported by 100% of the Tea Party, but there's no question that a large majority of those who claim membership in that movement, had also pinned their hopes for 2012 on her running for the presidency. The eight candidates who ran in the Republican primary were widely seen to be also-rans to her potential candidacy.
Choosing a clear front-runner was almost impossible for conservatives during the entire primary season. This would not have been the case, had Palin run. She would have owned the primary contest from the moment she announced, if she'd only done it.
In the end, center-right voters were faced with having to choose between a wide slate of candidates who mostly were indistinguished, and who did not embody the ideals and goals of the burgeoning movement to restore our nation's historic underpinnings quite the way Palin does.
This is based on two things. First, I think (can't prove) that Palin did polling the whole time her movie (which fell far below expectation---I know Bannon and his original deal), her "Alaska" show, and her bus tour were going on. They didn't move the dials. If she had been polling high teens when the primaries started, I think she would have been in.
Second---and this is anecdotal only, based on speaking to Tea Parties, Rotary (pretty conservative small businessmen), and conservative college kids from Young America's Foundation meetings---there was no enthusiasm for Palin. People here don't want to hear it, but I have found in conversations with all these groups that females (especially younger ones) do not like Palin as a political figure. I don't know the reason college-aged girls don't like her, but I think it has to do with the fact that she's too much like their mothers. As for the Tea Party groups I've spoken to, there is no stated reason, but the unwillingness to support her is obvious, even among very conservative people (especially women) I talk with. Probably the person they liked best was Newt, but none thought he could win. Santorum--- and I'm just repeating what I heard over and over---was viewed as sanctimonious and not a particularly good economics guy.
Part of the reason we got Romney was that there was this expectation that a knight on a white horse would come riding up, and throughout 2011 I kept saying here that there are four elements to a good candidate: 1) personality/appeal, 2) money, 3) organization, and 4) policies. Palin had money at one level, but could she raise the hundreds of millions from the Wall Street guys and the big business/Silicon Valley types? No. They really didn't like her. and the policies, but her organization was horrible. I have heard this from people very close to her who like her, but she's a control freak. This is understandable the way McCain's team messed with her. But it's a serious fault. I'm told that basic decisions a staffer should make in minutes took days, decisions that should take days took weeks. She had to personally approve everything. As for #1, she is extremely popular among a % of conservatives, but it is a very narrow but very deep loyalty.
Bottom line, I thought in 2011 Elmer Fudd could beat Obama, but as Romney's organizational failings showed ( and he was light years ahead of Cain or Gingrich or Santorum), you need people who know how to win and who will be ruthless. I thought at least Romney had the latter characteristic but I was wrong. His organization also proved little better than McCain's.
So, IMHO he are back to my original observations that the TP was losing momentum long before the primaries, and that above all it is too old to be a revolutionary force. No revolution in history has been led by the old. (likewise, no revolution in history has been SUSTAINED by the young). We must find a way, as Reagan did, to make conservatism appeal to the 25-40 year olds.