Except that you just said that Obama is more likely to win OH than PA. So Kerry + CO + NM + NV + IA + OH - PA = 277....which would mean he needs CO in order to win. He can't really afford to lose CO if he doesn't win PA.
I don't believe that Obama will do better in Ohio than Pennsylvania. if I gave that impression, I apologize.
I think he will run behind the Kerry2004 PA and OH numbers in relation to the national trend line but still hold on to Pennsylvania.
I agree that if he loses Pennsylvania and Ohio it becomes very difficult for him to win.... Kerry2004 - PA + CO + NM + NV + IA + VA is exactly 270.