Baring the unlikely event someone stronger gets in Simcox has my endorsement.
J.D. Hayworth is not going to challenge McCain in the primary. In fact, Hayworth endorsed McCain for President in both the 2000 and 2008 primaries. It seems sometimes that I'm the only freeper who noticed that, since his name is continually floated as a potential McCain challenger. Ain't gonna happen.
Endorse Simcox? If I had to choose between the two of them, I'd probably vote for him over McCain, but not until I know where he stands on other issues besides immigration. Any candidate I support will have to be at least as good or superior to McCain on key issues like right to life, traditional families, cutting government waste (one of the few areas where McCain is pretty solid, IMO), lower taxes, gun rights, and of coruse, the WOT -- I certainly won't back any surrender monkey's like the alleged "true conservative" from SC who wanted to sing kumbaya with terrorists. My guess is that Simcox is pretty solid on these issues, but my rule is thumb is always verify first. In any case, the drive-by media will villify Simcox as a hate-filled nut and portray him as a single issue candidate, so it's unlikely he's the one who can take out McCain.
I do think it's somewhat hypocritical of freepers to blast the MoveOn.org crowd in 2006 for "turning on their own party's presidential ticket nominee" and ousting LIEberman in the RAT primary, if we're willing to do the same to McCain in 2010 (though I admit there's a big difference as McCain has never been liked/trusted by conservatives, whereas liberals were happy with LIEberman for years, until he didn't do their bidding on the war issue)