Nothing, unless you want a nominee with the same disrespect for the First Amendment as John McCain.
You think Fred Thompson disrespects the 1st amendment because he has a friendship with McCain? I think he has a record and history that belies that. His ACU rating and votes:
http://www.freerepublic.com/focus/f-news/1794264/posts?page=667#667
I don't know what you have against him ... maybe you should say ... but his high 80's rating from the ACU and his ability to galvanize the Pubbie electorate is meaningful.