“There is no question that Romney has changed his positions on some issues, but so have some of the other candidates,” Geer said. “Why does the label stick to Romney but not his opponents? At least some of the answer lies in Romney’s Mormon beliefs.”
"We find that of those who accuse Romney of flip-flopping, many admit it is Romney’s Mormonism and not his flip-flopping that is the real issue,”............“Our survey shows that 26 percent of those who accuse Romney of flip-flopping also indicate that Mormonism, not flip-flopping, is their problem with Romney.”
"Benson noted that the pattern is especially strong for conservative Evangelicals. According to the poll, 57 percent of them have a bias against Mormons."
"The study’s findings suggest that criticizing Romney for flip-flopping is an effective campaign strategy because it sticks with two different groups: those who are genuinely concerned about Romney’s shifts on certain issues and those who use the label as cover for the fact that they do not want to vote for a Mormon for president."
--News from Vanderbilt University
Now, we already knew that this was the case, but now there's significant statistics and findings to go along with our assumption.