Further, I have the utmost respect for Mormons. If their most vocal critics exhibited even something close to their generally conservative voting behavior, this country would be in nowhere near the deep sh*t that we are.
I'm also aware that it is quite normal for voting to be influenced at least somewhat by group identification. Even more so if the particular group feels it is under constant attack from the mainstream. Catholics, for instance, were once a very loyal Democrat constituency for exactly that reason. Not so any more, because they no longer feel threatened. Jews are still a very loyal Democrat constituency, though that is changing, because the Democrat party is growing increasingly antisemitic.
If you look at exit polling in the states which have voted so far, Romney is still getting self-identified conservative voters in states where the Mormon population is negligible. So the answer to your question is that, of course, some of this support is identity politics, but some of it is also perception that his actual record of governance in Massachusetts is an anomaly because he was representing a very liberal constituency and he will govern far more conservatively as a president. Whether or not that is true is certainly a fair topic of debate. But it would be foolish to discount that said perception exists. (Anne Coulter is Exhibit A).
Feel better now?
I have not denied that part of their justification is that Romney’s record in MA is an anomaly. However, I’m suggesting that part of the motivation behind accepting this erroneous argument, for Mormons at least, is that Romney is a fellow Mormon, someone who they feel they can implicitly trust. That would explain the overwhelming majority of Mormons supporting him, not just a small amount comparable to the rest of the conservative base. It’s the overwhelming majority which I’m contending with here, not small amounts.
The options really, in the end, considering that Evangelicals and Mormons have similar political goals, are either that:
(1) Evangelicals accept arguments against Romney in large part because of their bias against Mormons;
(2) Mormons accept arguments in defense of Romney in large part because he is a fellow Mormon.
Considering the two diametrically opposed breaks for and against Romney amongst the “religious right,” it really comes down to these options. All things considered, option (2) makes more sense to me.