As the state of Bihar gears up for the upcoming Assembly election which will decide all 243 seats of the State Legislative Assembly, political observers are zeroing in on a handful of tightly-contested seats that may decide the overall outcome. The battle lines are drawn between the incumbent alliances and the opposition, and the seats where margins were razor-thin in 2020 are now being watched closely. With voter-list updates, shifting caste alignments and changed alliance math, these so-called "swing constituencies" are likely to play an outsized role in determining who forms the next government.
What are swing constituencies and why do they matter?
Swing constituencies are those electoral seats where past results have been close and where voter loyalties can shift between parties or alliances. These seats often decide elections because the overall majority hinges on small margins. In Bihar, many seats were won by very narrow margins in 2020 and changes such as voter list deletions, migration and alliance changes can flip them. The parties therefore pour extra resources, local leadership focus and campaign energy into these constituencies since winning them can make the difference between forming government or going into opposition.
Key swing seats that could decide the 2025 poll outcome
Here is a list of Assembly constituencies in Bihar that are being closely monitored as possible swing seats:
- Hilsa: The seat witnessed one of the most nail-biting contests of the 2020 Bihar Assembly elections, where JD(U)'s Krishnamurari Sharan, popularly known as Prem Mukhiya, defeated RJD's Atri Muni alias Shakti Singh Yadav by an incredibly narrow margin of just 12 votes. Both candidates secured nearly 37.35% of the total votes cast. Situated in Nalanda district, Hilsa has a long history of swinging between the JD(U) and RJD, making it a true bellwether seat. This time again, the seat will see a battle between JD(U)'s Krishnamurari Shara and RJD's Atri Muni.
- Barbigha: The 2020 contest turned out to be a razor-thin fight, with JD(U)'s Sudarshan Kumar narrowly defeating Congress candidate Gajanand Shahi by a margin of just 113 votes. Both contenders secured close to 33% of the total votes, reflecting a sharply divided electorate. The Congress' decision to continue staking its claim on the seat, despite tensions with the RJD over seat-sharing, highlights Barbigha's strategic importance within the I.N.D.I.A bloc's overall equation. This time, JD(U) has fielded Dr Kumar Puspanjay against Congress' Trishuldhari Singh.
- Ramgarh: RJD's Sudhakar Singh narrowly secured victory in Ramgarh during the 2020 Bihar Assembly elections, defeating BSP's Ambika Singh by just 189 votes, while BJP's Ashok Kumar Singh trailed close behind by about 2,800 votes. With all three major parties separated by barely two percentage points, it turned out to be one of the closest three-cornered contests in the state. As the 2025 elections approach, the RJD is aiming to unify anti-BJP voters, but the BSP's continuing hold over Dalit support could once again turn Ramgarh into an unpredictable battlefield. This time, the seat will seat a contest between RJD's Ajit Kumar, BJP's Ashok Kumar Singh and BSP's Satish Kumar Singh Yadav.
- Matihani: The 2020 Assembly election delivered a major surprise when the Lok Janshakti Part's (LJP) Raj Kumar Singh edged past JD(U)'s Narendra Kumar Singh by a slim margin of just 333 votes, with CPI(M)’s Rajendra Prasad Singh trailing by only around 400 votes. All three candidates secured close to 29% of the total vote share, making it one of the most unpredictable contests in the state. This time, the JD(U) has fielded Raj Kumar Singh against RJD's Narendra Kumar Singh alias Bogo Singh at this seat.
- Bhorey: JD(U)'s Sunil Kumar emerged victorious in 2020 by a narrow margin of only 462 votes against CPI(ML)'s Jitendra Paswan, with both candidates securing over 40% of the total votes. The CPI(ML)'s strong performance highlighted its expanding influence among Dalit and agrarian voters in rural areas. With the Left now officially part of the I.N.D.I.A bloc, Bhorey is once again expected to witness a straight contest between the NDA and the Left in the 2025 elections. This time, Communist Party of India (Marxist-Leninist) (Liberation) has fielded Dhananjay against JD(U)'s Sunil Kumar at this seat.
- Dehri: The seat witnessed another nail-biting contest in the 2020 Bihar Assembly elections, with RJD's Phate Bahadur Singh narrowly defeating BJP's Satyanarayan Singh by a margin of just 464 votes, as both candidates secured over 41% of the vote share. The seat has historically reflected the larger political mood of the state, making it a key indicator of the overall trend. Given its significance, both alliances are likely to mount high-voltage campaigns in Dehri this election season. This time, Lok Janshakti Party's (Ram Vilas) Rajeev Ranjan Singh has been pitted against RJD's Guddu Kumar Chandrawansi at this seat.
- Bachhwara: The 2020 election turned into a fierce Left vs BJP showdown, where BJP's Surendra Mehata narrowly defeated CPI's Abdhesh Kumar Rai by a slim margin of just 484 votes. Both candidates secured close to 30% of the total votes. The CPI's long-established grassroots base in the constituency continues to hold strong. However, with the Left now contesting against the Congress in several seats this time, internal strains within the I.N.D.I.A bloc are becoming more visible despite ongoing efforts at coordination. This time, the seat the seat will see a battle between BJP's Surendra Mehta, CPI's Abdesh Kumar Rai and Congress' Shiv Prakash Garib Das.
- Chakai: The seat witnessed one of the most surprising results of the 2020 Bihar Assembly elections when independent candidate Sumit Kumar Singh edged past RJD's Savitri Devi by a narrow margin of 581 votes. Since then, Singh has aligned himself with the NDA, which is expected to boost his prospects through the combined strength of the BJP-JD(U) alliance. However, the RJD is keen to win back the seat, setting the stage for another tight contest. This time again, JD(U) has fielded Savitri Devi against Sumit Kumar Singh against RJD leader Savitri Devi at this seat.
- Kurhani: The 2020 Assembly contest turned into a photo finish, with RJD's Anil Kumar Sahni narrowly defeating BJP's Kedar Prasad Gupta by just 712 votes. The RJD secured 40.23% of the vote, while the BJP followed closely with 39.86%. Situated in Muzaffarpur district, Kurhani has frequently swung between rival camps and even witnessed a bypoll in 2022. The seat is set to see a battle between BJP's Kedar Prasad Gupta and RJD's Sunil Kumar Suman in the upcoming election at this seat.
- Bakhri: CPI's Suryakant Paswan secured a narrow victory over BJP's Ramshankar Paswan in the 2020 elections, winning by a margin of just 777 votes. Both candidates garnered over 43% of the total vote share, reflecting a fiercely contested race. As one of the last remaining strongholds of the Left in Bihar, Bakhri will be a key constituency to watch this time, especially as the NDA intensifies its efforts to expand influence in Scheduled Caste-reserved seats. This time, the seat is set to witness a contest between CPI's Suryakant Paswan and Lok Janshakti Party's (Ram Vilas) Sanjay Kumar.
Bihar Assembly Elections 2025
Earlier this month, the Election Commission announced the schedule for the Bihar Assembly elections. The 243 Assembly seats will go to the polls in two phases on November 6 and November 11, with the counting of votes scheduled to take place on November 14. The NDA led by the BJP and JD(U) will be up against the I.N.D.I.A bloc, led by Tejashwi Yadav of the RJD, the Congress, the CPI (ML) led by Deepankar Bhattacharya, the CPI, the CPM, and Mukesh Sahani's Vikasheel Insaan Party (VIP). The new entrant, Prashant Kishor's Jan Suraaj, has also fielded candidates on all 243 seats of the state.
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