Ever since roughly 1890, Mormons have been trying to compensate for the weirdness of their founding era by closely emulating mainstream middle class white American culture (which hasn't been that hard for them since they tended to start out as mainstream Northwest Europeans).
This worked well for them subjectively in terms of social acceptance within America (nobody much cares, or even notices, that the Democratic Senate majority leader, Harry Reid, is a Mormon).
And, this Mormon strategy of being more mainstream than the mainstream also worked well for them objectively, in terms of prosperity, safety, sobriety, honesty and a host of other measures of good things, because the 20th Century American middle class mainstream had lots and lots of good values.
But now, a representative (indeed, exemplary) Mormon is trying, like John F. Kennedy and Barack Obama, to lead his people to the ultimate symbolic level of acceptance, the Presidency. To Mormons, Romney represents the beau ideal of their culture.
Perhaps we'll have a different perspective after the debates, but at present it appears that the Mormon strategy has broken down at making the last leap. Contemporary Americans find Romney, and Mormons in general, weird and creepy and offputting and suspicious. And that's less because Mormons' great-grandfathers were polygamists than because Mormons try hard to act like the mainstream middle class white Americans who took the human race to the Moon, and what could be more uncool (and maybe downright racist) than that?
In 1928, voters rejected the first Catholic presidential candidate, Al Smith. This caused much soul-searching among Catholics, and the overall response was to redouble their efforts to fit into the American mainstream. Catholic schools became ever more Americanized (e.g., relative to Quebec's). The next Catholic nominee, JFK, was almost a parody of upper class WASPishness: winters in Palm Beach, Choate, Harvard, naval officer, sailing, golf, etc.
As a candidate, JFK gave a famous speech to suspicious Protestant ministers in Houston that allayed suspicions that he would let Catholic internationalism conflict with Protestant American nationalism. This speech is spun these days as a triumph over Protestant bigotry, but if you actually read JFK's speech, it was a near complete capitulation to Protestant American nationalism. Catholic Rick Santorum read it for the first time earlier this year and, being basted in 21st Century minoritariansm, he was shocked by how the minority candidate had fully endorsed the fundamental prejudice of the majority and promised to live up the majority's demands.
After JFK's election and, perhaps more importantly, martyrdom, American Catholic distinctiveness and sense of peoplehood receded.
But what will happen among Mormons if Romney is defeated in sizable part because he's so Mormon in affect, values, and behavior? Will they redouble their efforts to be even more what they are? Will they decide they have to loosen up and get funky? Will we see more ads on TV featuring Mormon Tongan NFL players?
Or, feeling rejected as a people, will Mormons go off in a new, subversive direction of ... what?
Mormons aren't a huge group (usually said to be about 9 million). And they aren't hugely talented. They generally seem to be about the white American average — but that puts them increasingly above the American average. And they are better organized, more cohesive, and less dysfunctional than most. So, if they move in a particular direction, it could be moderately significant.
The most likely reaction would probably be to modernize by accelerating the Third Worldization of Mormonism. That would be the easy, socially acceptable path. But that way leads to irrelevance because nobody cares much about nonblack nonwhites, especially ones who choose to assimilate into polite Mormonhood rather than riot over YouTube videos.
Perhaps, though, there are other, more unexpected directions that insulted, alienated Mormons could turn. I don't know enough about them to guess what those might be, however.