In 2015, BJP overtakes communist party of China to become world largest party. According to the current data BJP has more than 18 crore registered members which are almost twice as many members of the communist party of China.
If today we look about the political supremacy of BJP, it has 303 members in the Lok Sabha, which is more than 55% of the total seats in this house. Out of 29 states of India, 13 States have BJP majority Government, and four others have BJP supported government.
History of BJP
On 21 October 1951, Dr Shyama Prasad Mukherjee laid the foundation of Bhartiya Jan Sangh with the help of RSS. He was a member of the Indian constituent assembly before this. He was also appointed minister of industries and supply in Jawaharlal Nehru’s first cabinet. But in the against of Nehru Liaquat pact of 1950, he resigned and become the founder and first President of Bhartiya Jan Sangh. At the time the main purpose of this party was to protect the cultural identity of Hindus in the independent India and simultaneously opposing Congress, mainly Jawaharlal Nehru’s private Muslim apportionment policy.

The Jan Sangh demanded complete merger of Jammu and Kashmir with India. In the general election of 1951-1952, Jan Sangh won only three seats. After the death of Shyama Prasad in 1953, pandit Dindayal Upadhyay give a new direction to Jan Sangh. Till 1967, while being the general secretary of Jan Sangh, he paid special attention to strengthen its ground level organisation. Jan Sangh won 35 seats in the general election of 1967 and emerged as the third largest political party in India.
the Jan Sangh also formed the United legislature party in association with other non-Congress affiliated, region political parties of the Hindi speaking regions and formed government in Uttar Pradesh, Madhya Pradesh and Bihar.
Atal Bihari Vajpayee started to lead the Jan Sangh after Dindayal Upadhyay. The main agenda of this party was cow slaughter ban, end of special status of Jammu & Kashmir and uniform civil code.
thousands of activists from Jan Sangh arrested due to a nationwide protest by them against the emergency of 1975. After the emergency of 1975, in 1977 Jan Sangh formed a new political party with the collision with three other parties (socialist party, congress o and Bhartiya Lok dal). The main purpose of this party was to combat Indian National Congress and won.
In the general election of 1977 Janata party formed the government and Morarji Desai become the first non-Congress prime minister and Atal Bihari Vajpayee external minister.
But due to lack of compatibility among its constituent parties and different of ideologies, the collision government fell. In the general election of 1980, Janata party performed very poorly and own just 31 seats.
Finally on 6th April 1980, BJP was formed in the leadership of Atal Bihari Vajpayee and Lal Krishna Advani.
The rise of Bhartiya Janta party
the first president of the BJP was Atal Bihari Vajpayee who also remained the head of the Jan Sangh. In the general election of 1984, BJP could win only two seats. After this, Lal Krishna Advani was appointed the president of the party and the party started moving forward with the Hindutva ideology. In early 1980, Vishwa Hindu Parishad had started a moment regarding Ram Janmabhoomi and Babri masjid. BJP joined this movement in the leadership of Lal Krishna Advani and made Ram Janmabhoomi issue a part of its electoral manifesto. In a way, this was the issue on which BJP struggled and made a major influence. In the general election of 1989, the party got 86 seats and government formed with coalition. Vp Singh became prime minister.
The Ram Janmabhoomi Movement
By the time 1990 came, the name of Atal Bihari Vajpayee and LK Advani became known to every people of the country. In 1990, Advani launched erase Yatra from Somnath to Ajodhya to demand the construction of Ram temple. During this Yatra, Advani blamed on government of Muslim appeasement and pseudo secularism in his speeches. Advani and his associates were finally stopped and detained by the Lalu Prasad Yadav led Bihar government in Samastipur. Despite of this, thousand number of carsevaks arrived Ajodhya. The then UP Government led by Mulayam Singh Yadav issued orders to detain car sevaks. Meanwhile, there was a violent between car sevaks and paramilitary forces. Many car sevaks were killed and violent changed into riots. BJP withdraw its support from the Vp Singh Government and got 126 in the fresh elections.

On 6 December 1992, Babri masjid wale demolished by a mob of carsevaks. After this incident, riots started in country and thousands of people were killed. Lal Krishna Advani and other leaders were arrested of inciting the incident and hate speeches.
Many historians believe that it was a not normal incident it was a pre-planned conspiracy. Along with Ram Janamabhoomi movement, BJP started a Ekta Yatra in his president Murali Manohar Joshi on 11 December 1991. This Yatra started from Kanyakumari with the passing through 14 States and ended on 26 January 1992 in Srinagar.
In organising these two, India’s current PM Narendra Modi, who played an important role, so we understand that the future leadership of India was also being prepared amidst these moments.
The BJP turned into NDA
In decade of 1990, many regional parties were emerging but no one was able to compete Congress alone. BJP joined hands with this parties to form NDA of the national democratic alliance. They were directly contesting with the Congress in form of UPA.
Atal Bihari Vajpayee became India’s pm three times but only once he was able to complete his term. This was the era of coalition government where the government was formed or fell according to the mood of constituents. But BJP was emerging as big party. When Atal ji government from 1999 to 2004, his rule was highly appreciated. But Congress returns to the power in form of UPA in 2004. Even after the continuous raising of questions on Congress administration, UPA completed its two consecutive terms. It seemed like that same old era of Congress back.
The NDA turn BJP
UPA’S second term was marked by a series of corruption charges and skyrocketing inflation. In such situation, the people of country wanted change. Under the leadership of the then chief minister of Gujarat Narendra Modi, BJP returned in power in 2004 with full majority. In the general election of 2019, BJP again won with full majority.

Recording to data of 2015, BJP became the largest political party of world with registered member of more than 18 crore.
Source: https://economictimes.indiatimes.com/news/politics-and-nation/bjp-becomes-largest-political-party-in-the-world/articleshow/46739200.cms