As far as Texas, you have to take a look at the white downscale economic vote. Obama does great among upper income whites in the north and west. No doubt. It's a little different in the border and southern states among poor whites. I'll give you an example. Survey USA did a head to head survey in Kentucky February 5th.
McCain 52 Hillary 42
McCain 61 Obama 32
Obama will give back some votes and actually run behind Kerry among whites in this demographic in the South.
There's a world of difference between Texas and Kentucky. Appalachia is one of the few areas would Clinton would do better. Ozarks also. Anyhow, neither one is going to get any electorals in the South (except
maybe AR for Clinton) including Texas so the point seems moot.