Without a doubt, if Romney were the Republican nominee, there would be a lot of scrutiny from the left. It would likely come from a lot more angles than any scrutiny he faces from the right. Here is an article I easily found from a lefty. It is a year old, it is interesting, and just a small taste of what would be seen in uncountable publications from the left once it is time for them to put the pedal to the metal. They will easily be able to draw on the fears of both the right and the left.
And there is an even more interesting wiki article on the assasination of Joseph Smith, the first prophet and founder of the Mormons who holds the keys to heaven.