There are no facts and figures given here that support the conclusion. These data and statistics are lumped and include the swayed. the only way to get data on real R voters is roughly to compare straight R voter numbers for a john doe(R) against an incumbent D in prior mid term, or presidential year elections with this one.
Read the document at the link. It's 85 pages with a lot of detail, providing lots of evidence for their summary statements.
One is here, I am sure there are many more similar ones.
http://www.freerepublic.com/focus/f-news/1736379/posts?page=111#111
http://www.freerepublic.com/focus/f-news/1736379/posts?page=112#112