Allies again, why AIADMK, BJP face uphill battle against DMK in 2026 Tamil Nadu polls

Complicating matters for the alliance are the former AIADMK leaders who have sided with the BJP in recent years, including former CM O Paneerselvam or OPS and T T V Dhinakaran, who now heads his own outfit AMMK. It remains to be seen how the BJP-AIADMK alliance will accommodate such parties in the NDA fold. While announcing their alliance in Chennai last week, Union Home Minister Amit Shah said: “The BJP will not interfere in the AIADMK’s internal matters or ask them to reinduct ousted leaders. There will not be any interference.”

In the 2016 Assembly polls, the last to be led by former CM and AIADMK chief late J Jayalalithaa before her demise later that year, the AIADMK had returned to power by winning 135 of the state’s 234 Assembly seats. Going solo in the polls, the AIADMK had contested every seat, securing 40.8% of the vote share – well ahead of its principal rival DMK’s 31.6%.

The BJP, also contesting independently then, failed to win a single seat, with all but eight of its 188 candidates forfeiting their deposits. At 2.8%, the BJP’s vote share rose only marginally from the 2.2% in the 2011 polls.

But after Jayalalithaa’s death, the AIADMK plunged into a prolonged tussle over succession. Several senior leaders rebelled and were later expelled. Though the party fought the 2021 polls under the joint leadership of former CMs Paneerselvam and Edappadi Palaniswami or EPS — who is the current party general secretary — it was unable to overcome its 10-year anti-incumbency, while the DMK-led alliance swept to power with 159 seats. Paneerselvam has since fallen out with the AIADMK after locking horns with Palaniswami over the party’s leadership, and was expelled in 2022.

Significantly, the 2021 elections marked the first Assembly battle that saw the AIADMK and the BJP contest together under a seat-sharing pact, with their alliance earlier restricted to the Lok Sabha polls.

In the 2021 polls, while the BJP managed to win four seats – only the third time the party won any Assembly seats in the state – the AIADMK’s tally dipped to 66 seats. Contesting most of the seats, the AIADMK also saw its vote share drop sharply to 33.3%, while the BJP’s vote share fell marginally to 2.6% despite contesting just 20 seats.

In September 2023, amid growing tension between ex-state BJP chief K Annamalai and the AIADMK over the former’s remarks against the AIADMK leadership, the parties snapped ties and went on to contest the 2024 Lok Sabha polls independently. But neither of them was able to make an impact as the DMK-led INDIA bloc maintained its dominance in the state by bagging all 39 Lok Sabha seats. Besides the DMK and Congress, the INDIA alliance comprised the Left parties, IUML, VCK, MNM, MDMK and KMDK. In the 2019 parliamentary polls, the DMK-led alliance had won 38 seats in a performance that proved to be a prequel to the 2021 victory.

The 2024 Lok Sabha polls marked a significant improvement for the BJP, at least in terms of vote share. Contesting 23 seats, the second highest since the party contested 37 seats in 1996, the BJP managed to raise its vote share to 11.38% from 3.7% in 2019, when it had contested just five seats.

Among the BJP’s NDA allies in the 2024 Lok Sabha polls, Vanniyar caste leader S Ramadoss’s PMK contested 10 seats, former Congress leader G K Vasan’s Tamil Maanila Congress (Moopanar) contested three seats, and the AMMK two seats. But all of them drew a blank. While the PMK secured 4.35% votes, the other two allies managed less than 1%.

In the 2024 polls, the AIADMK contested 34 seats and secured 20.7% of the vote share, up from 18.7% in 2019, when it had contested 21 seats and was allied with the BJP. The AIADMK’s allies then included the DMDK, founded by the late film star Vijayakanth, that failed to win any of the five seats it contested and secured a vote share of just 2.61%.

A breakdown of the 2024 Lok Sabha poll results at the Assembly-segment level shows that despite failing to win a seat, the BJP finished as the runner-up in 59 segments and third-best in 64 segments. Of these, the BJP secured more than 20% of the vote share in 56 Assembly segments and over 30% in 20 segments. However, the BJP did not lead in any segment in the state.

[MAP: BJP’s vote shares]

A map of the BJP’s vote share shows that its strongest performance came in the Assembly segments concentrated in the southern region around the Kanniyakumari district, the western region around Coimbatore, and a northern pocket around Vellore.

However, among the 15 Assembly segments that the BJP contested both in the 2021 Assembly polls and the 2024 Lok Sabha elections, the party saw its vote share fall in all but one segment in the intervening period. In 2021, of the 20 Assembly seats it contested, the BJP had won four and finished as the runner-up in 16 with vote share exceeding 30% in 14 seats.

On the other hand, an Assembly-segment level breakdown of the AIADMK’s performance in the 2024 Lok Sabha polls shows that the regional party did not fare much better than the BJP. The AIADMK was the leading party in just eight Assembly segments and the runner-up in 126. It finished third in another 59 segments and fourth in 11.

The AIADMK’s vote share spread, however, paints a more promising picture. The party secured more than 40% vote share in 10 segments, between 30% and 40% in 33 segments, and between 20% and 30% in 82 segments. Worrying for the party were the 62 segments where it received between 10% and 20% vote share, and 17 segments where it fell below 10%.

The map of the AIADMK’s vote shares show the party is most dominant across a belt in central Tamil Nadu – stretching from the coastal district of Viluppuram in the west, through districts like Kallakurichi, Salem, Erode and Namakkal in the central region. It is also strong in pockets around Nagapattinam and Ariyalur close to the coast.

[MAP: AIADMK’s vote shares]A comparison of the AIADMK’s vote shares in the 2021 Assembly polls and the 2024 Lok Sabha elections, however, shows that the party’s vote share fell in 170 of the 171 Assembly segments it contested in both polls. In 2021, of the 191 Assembly seats it had contested, the AIADMK won 66 and was runner-up in the remaining 125 seats.

With the 2024 Lok Sabha polls pitting the AIADMK and BJP against each other in 20 seats involving 115 Assembly segments, the two parties may have ended up cutting into each others’ votes, given that the AIADMK only led in four of these segments and the BJP none. In these 115 segments, the INDIA bloc led in 111 segments – the DMK in 58, the Congress 30, the Left parties18 and the VCK in four. This analysis does not include the other BJP and AIADMK allies owing to their significantly smaller vote shares and the point that their roles in the new alliance are still uncertain.

Among the 111 segments where the INDIA bloc led in 2024, the combined vote shares of the AIADMK and BJP would have exceeded that of the leading party in 42 segments, assuming a perfect transfer of votes between them. These 42 segments were led by the DMK in 23, the Left 10, the Congress seven, and the VCK in two.

[MAP: AIADMK and BJP combined vote shares]There are 11 segments where the combined AIADMK-BJP vote share exceeds 50%, 60 segments where it is between 40% and 50%, and 39 segments between 30% and 40%.

However, overall, at the Assembly-seat level in the 2024 polls, the INDIA bloc had an upper hand in 221 segments, with the AIADMK-led alliance leading in 10, and the BJP-led NDA leading in just three (with all three led by the PMK).