Mitt Romney was the first Mormon to receive a presidential nomination from a major political party, but surprisingly he received a smaller percentage of the Mormon vote than evangelical Christian George W. Bush did in 2004. 

According to Pew Research's exit poll data, 78% of Mormons voted for Romney in 2012. In 2004, 80% of Mormons voted for Bush. 

On the other hand, Romney received the same percentage of evangelical voters (79%) as Bush did in 2004.