The Bharatiya Jana Sangh (abbrv. BJS), commonly known as the Jan Sangh, was an Indian nationalist political party that existed from 1951 to 1977 and was the political arm of Rashtriya Swayamsevak Sangh (RSS), a Hindu right-wing organisation. In 1977, it merged with several other left, centre and right parties opposed to rule of the Indian National Congress and formed the Janata Party. After the Janata Party split in 1980, it was re-formed as the Bharatiya Janata Party (BJP) in 1980, which is currently India's largest political party by primary membership and representation in Lok Sabha.