1,123 defections in 15 years:
Over the three Lok Sabha terms between 2009 and 2024, 1,123 representatives from the Lok Sabha, Rajya Sabha and state assemblies switched parties. While 318 members defected during the 15th Lok Sabha, the number increased to 434 in the 16th, but came down to 371 in the 17th Lok Sabha.
Defection is much more common in assemblies, mainly due to the higher number of elected representatives. During the 15th Lok Sabha term, 86 per cent of those who switched parties were MLAs, while 13 per cent were Lok Sabha MPs and only 1 per cent were Rajya Sabha members.
Most of the defections came from the three major parties – Congress, BJP and Bahujan Samaj Party (BSP).
Meanwhile, BJP, Congress and Trinamool Congress (TMC) are the top three parties that have received the highest number of defecting members. The BJP attracted 14 percent defectors during the 15th Lok Sabha term, which increased to 38 percent in the 16th and fell to 31 percent in the 17th. Congress’s share dropped from 17 percent to 10 percent, where it remained. During the same period, AITC’s share gradually increased from 2 percent to 8 percent.
Due to the Tenth Schedule of the Constitution, elected representatives in Parliament and State Assemblies cannot freely change parties. In practice, such members usually take one of two paths: either they first resign their seat and then join another party (triggering a by-election), or they become part of a group that includes at least two-thirds of their party’s MLAs, which qualifies as a merger and avoids disqualification.
Former Lok Sabha Secretary General PDT Acharya said that politicians change parties for two broad reasons. First, many in the opposition left their parties in search of better prospects, especially when they found electoral space within their own party limited, and often joined the ruling party. Second, some members of ruling parties also defect, usually when they anticipate a change in political coalition or the emergence of an alternative formation that might improve their prospects.
“Elected representatives and political parties often have a better understanding of the ground realities and future electoral prospects than external political experts. In this context, ideology has become less important for many politicians today, with strategic considerations and electoral feasibility being given priority,” Acharya said.
Looking at electoral behaviour, the share of Lok Sabha MPs switching parties before contesting re-election has also fluctuated. Of the total MPs contesting re-election before the 15th Lok Sabha elections, about 10 per cent changed parties, before the 16th Lok Sabha elections 9.5 per cent did so and before the 17th Lok Sabha elections this figure increased to 12.9 per cent.
At the regional level, there is significant variation in the distribution of MLAs switching parties during the 17th Lok Sabha term. North East had the highest share at 29 percent, followed by North at 23 percent. The South contributed 17 percent, the East 15 percent, the West 14 percent and Central India only 2 percent.
