What nonsense. Clinton's "Southern roots" weren't a problem nor are Hillary's transplanted ones. The candidate the Dems would love to nominate is Gore, another Southerner. The South is the GOP's power base so nominating a candidate from NY or Mass would be far worse for its chances than nominating Fred Thompson.
You are right. Fred Thompson is more electable in the Midwest than McCain or Giuliani (and certainly more so than Romney) because he can connect with populist Democrats for whom illegal immigration, right to life and the Second Amendment are important issues. He also connects with them on a personal level, because he is a down to earth, great guy and it comes through. He has a great rags to riches story, pulled himself up by his own bootstraps, started out dirt poor, and really made something out of himself (like RR). None of the other three can connect with populist Democrats like Fred. This is the key to electability in the Midwest, not whether someone lives north of Mason-Dixon.