Matthew Lee Anderson, following Ross Douthat, re-imagines a trope:
I owe the point to Ross Douthat’s new book Bad Religion, where he points out that John Winthrop’s famous "city on a hill" line was something of a warning that if America failed to do well than America would be judged accordingly. Douthat expands the thought, pointing out that in Lincoln’s Second Inaugural he "invokes providentialism to explain a chastisement, rather than to boast of America’s particular virtue or celebrate its particular mission in the world." A political version of the via negativa, if you will, where exceptionalism is invoked to caution America from going wrong.
This is of a piece with Mormon (and Obama's) understanding of the concept. Just not Romney's.