On the fourth anniversary of the UPA II, Parliamentary Affairs Minister Kamal Nath told NDTV that Congress Vice President Rahul Gandhi should replace Manmohan Singh as the prime ministerial candidate of the UPA in the next general elections.As far as Mamata Banerjee is concerned, it was an issue of West Bengal politicsThe regional parties are state-centric, the government needs to have national focus.Elections will take place when they take place. As things stand now, there are no possibilities of early polls.