I'd really prefer this not become an issue. The last Gallup poll I looked at on the matter seemed to suggest Democrats may be slightly more likely than Republicans or indies to discriminate against a Mormon candidate for President of the United States. It would be in dreadful taste for folks on the left to attack Romney for his faith and I do hope it will not at all be an issue in the general election.
There is likely a bias associated with disdain for Mitt Romney the man rather than the Mormon faith. Romney is this year's Republican candidate and the first Mormon major party nominee. The association is too strong to poll this cycle. I would have to compare it with similar past and future polls.