Communists have ruled Bengal for 40 years and no one can imagine anyone from there ( communists ) to be PM in next 40 years. The Congress has been rather silly in upping the ante in a communally polarized society which suits Modi well..the more you accuse him of communalism, the more votes he will get BECAUSE that is the badge of honour for him. Prove him to be "maut ka saudagar" and more will vote for him. Modi cannot be defeated in Gujarat because people in Gujarat will never accept a liberal, secular leader. PERIOD. Modi may try now to become a more accceptable
As for rest of the country - I think - election arithmetic is a little different.