I guarantee it's a lot higher than that, but people won't admit it.
Another recent poll showed the number as high as 26% of Republicans that would not vote for a Mormon.
http://pollposition.com/2011/09/14/vote-mormon-for-president/
And I saw another poll that I can’t find a link to at the moment that said something like 40%+ of evangelicals know somoene who wouldn’t vote for a Mormon for president.
Romney can’t win if even 5% of Republicans stay home much less 20% or more. A vote for Romney is a vote for Obama.
They're included in the percentage that won't vote for an unprincipled flip-flopping RINO.