DeMint is "splitting not just from Graham, but from Sanford and perhaps leading some of the Bush faction that doesn't want to go over to McCain," said Larry Sabato, director of the University of Virginia Center for Politics. McCain "is not conservative enough for many of the conservative Republicans of South Carolina."
Oh yeah? You're forgetting Duncan Hunter, for whom FR was aflame at the time.
DeMint is obviously not a reliable conservative, because he cannot answer "No" to the "Are you now, or have you ever been, a Romney supporter"? query.
That was 2008. However, DeMint supported Mitt starting in late 2006, fund raising for Mitt.