Tamil Nadu Elections 2026: How Reserved Seats Shape Power in TN

This article examines Tamil Nadu's 46 reserved constituencies, analysing how AIADMK and DMK performances differed in 2016 and 2021 and what these shifts imply for the 2026 election, with emphasis on regional belts and coalition impacts.

The 46 reserved constituencies in Tamil Nadu have long carried an outsized political weight. Made up of 44 Scheduled Caste seats and two Scheduled Tribe segments, these constituencies often mirror the broader electoral mood of the state. In both 2016 and 2021, the alliance that dominated these seats went on to form the government, reinforcing the belief that reserved constituencies are a key battleground in Tamil Nadu politics.

In the 2016 Assembly election, the AIADMK under J. Jayalalithaa performed strongly in these constituencies and used that advantage to retain power. Out of the 46 reserved seats, the party contested 44 and won 31, giving it a decisive edge over its rivals. The performance was particularly impressive in the western and southern regions, where the AIADMK enjoyed a firm social and organisational base. Those gains in reserved constituencies played a major role in helping the party return to office.

The DMK, by contrast, struggled in the same election. It contested 35 reserved seats but managed to win only 13. Its ally Congress contested nine such seats and won just two. Other parties also failed to make an impact. The PMK contested all 46 reserved constituencies but did not win a single seat. The VCK, contesting eight seats as part of the People's Welfare Front, also drew a blank. The outcome underlined AIADMK's strong grip over these politically significant segments in 2016.

The picture changed dramatically in the 2021 Assembly election. The DMK-led alliance, headed by M.K. Stalin, turned the map of reserved constituencies in its favour and in doing so laid the groundwork for its return to power. The DMK contested 27 of the 46 reserved seats and won 22, a sharp improvement over its 2016 showing. This turnaround was one of the clearest indicators of the anti-incumbency sentiment building against the AIADMK government.

AIADMK's performance in the reserved constituencies declined steeply in 2021. The party contested 33 such seats but won only 14, less than half of what it had secured five years earlier. That fall was politically costly, as it exposed the weakening of the party in segments that had once formed an important pillar of its electoral success.

The DMK alliance also benefited from stronger contributions by its partners. Congress improved significantly, contesting eight reserved constituencies and winning six. The VCK, which had failed to open its account in 2016, became more effective after joining the DMK-led front. It contested four reserved seats in 2021 and won two, including Arakkonam and Kattumannarkoil, giving the alliance both symbolic and numerical gains.

There were also notable regional shifts. Of the two ST-reserved constituencies, Yercaud and Senthamangalam, AIADMK had won both in 2016. In 2021, however, the DMK captured Senthamangalam, while Yercaud remained with AIADMK. The Kongu belt too, long regarded as an AIADMK bastion, did not back the party with the same force in reserved constituencies.

That is why these 46 seats will once again be watched closely in 2026. In Tamil Nadu, reserved constituencies are not merely a category on the electoral map. They are often a signal of where power is heading.