BJP lost its base considerably in 2004. Drop from 183 to 138 (loss of 45 seats) was not because of TN or Andhra. How many seats BJP had in TN AP? 5? This loss is despite an impressive show by BJP in MP & Rajastan. Now they are loosing the battle in both those places and andin next elections they will suffer big losses in both MP and Rajastan. They wont probably compensate that loss from elsewhere.
In Bihar and Punjab being part of the opposition they benefitted from anti-incumbency. They are riding on strong allies shoulders. This week they lost 2 LS elections in Chatisgarh and Jharkand. By now BJP leadership might have understood what is in store.