I think if there is any error in polling this time around, it will be underestimating the Mormon turnout. Romney WAY overperformed in the primary states with relatively heavy Mormon populations. Below are the top 10 percentages for Mormon states and their polling status. Nevada is the key toss-up state with a big enough Mormon vote to push it over the edge to Romney. Mormons also should guarantee Arizona for Romney. Not sure if they can help enough in Montana or Oregon.
Utah 71.76% RED
Idaho 26.63% RED
Wyoming 10.10% RED
Nevada 7.41% TOSS-UP
Arizona 5.45% LEAN RED
Montana 3.58% LEAN BLUE
Hawaii 3.46% BLUE
Oregon 3.15% LEAN BLUE
Washington 3.10% BLUE
Alaska 2.86% RED
Romney is at risk of losing Montana? That's new to me...