It has been reported that Mitt Romney may have his own form of "Bradley Effect" - polling higher than final vote totals. Like the race issue with Bradley and Wilder, some people may be reluctant to tell pollsters that they won't vote for Romney because of his Mormonism.
Personally, I doubt that factor will come into play. As you may have noted, there is absolutely no reluctance to express an anti-Mormon bias among the anti-Romney forces on Free Republic.
This segment of the voting public wears their anti-Mormonism on their sleeve -- they wouldn't hide it from a pollster.
They probably fit in the "undecided" or "somebody else" segment of most polling samples.
Tri-State area?