Aam Aadmi Party (AAP) leader Dilip Pandey on Tuesday said a referendum on statehood for Delhi was "not unconstitutional" and the BJP and Congress had also asked for it in the past.Addressing a press conference here, Pandey said the demand for statehood to Delhi was the first pro-people issue before the central government and hoped that the prime minister would accept it.Pandey said the present discussion on full statehood for the national capital was not an AAP initiative but had been raised by the Bharatiya Janata Party and the Congress as early as in 1993.Congress leader Ajay Maken on Monday had termed Delhi Chief Minister Arvind Kejriwal's idea of conducting a referendum on statehood for Delhi as "unconstitutional and a dangerous ploy with grave fallout".In a cabinet meeting last week, Kejriwal stressed that the priority of the urban development department of the Delhi government should be on gaining statehood for the national capital.