Incumbent parties won 53% of state by-elections since 2009, shows data

Data from 709 by-elections since 2009 shows incumbent parties won 53% of contests, while opposition parties secured 47%, reflecting a closely contested political landscape

Incumbent parties have retained a slight edge over the Opposition in Assembly by-elections over the past 17 years, winning 53 per cent of the 709 contests held between 2009 and August 2026, according to an analysis of Election Commission data. The latest bypolls in Bihar, Madhya Pradesh, and Gujarat, where opposition parties — Jan Suraaj and the Indian National Congress — won two of the three seats, reflect the increasingly competitive nature of these contests. 

Of the 709 bypolls, incumbent parties won 53 per cent, while opposition parties secured 47 per cent. The performance of both camps followed a similar trajectory over the period. Opposition victories rose from 62 during 2009-2013 to 125 in 2019-2023 before declining to 47 between 2024 and August 2026. Incumbent victories increased from 66 in 2009-2013 to 125 in 2019-2023 before easing to 65 in the latest period. 

At the party level, the Bharatiya Janata Party (BJP) accounted for the largest share of victories by incumbent parties at 30 per cent, followed by the Indian National Congress at 27 per cent, and the All India Trinamool Congress (TMC) at 6 per cent. Among opposition victories, the Congress led with a 41 per cent share, followed by the BJP at 17 per cent and the Samajwadi Party (SP) at 8 per cent. 

While the number of Assembly by-elections has increased over the years, a majority have coincided with Lok Sabha election years. Overall, the data show that while opposition parties have steadily expanded their presence in Assembly bypolls, incumbent parties continue to hold a narrow advantage, keeping these contests closely fought.