Tamil Nadu legislative assembly election was held on 6 April 2021 to elect the representatives of the 16th Tamil Nadu assembly. Elections were held for all the 234 constituencies in the assembly. The Election Commission of India announced the schedule for the elections on 26 February 2021. The Dravida Munnetra Kazhagam (DMK) won the election, ending the decade-long reign of the All India Anna Dravida Munnetra Kazhagam (AIADMK), and M. K. Stalin was sworn in as the 12th Chief Minister of Tamil Nadu.

The poll was Tamil Nadu's first assembly election after the demise of the two most prominent chief ministers in the state's modern history, J. Jayalalithaa of the AIADMK, and M. Karunanidhi of the DMK, who died in 2016 and 2018, respectively. With the AIADMK winning the 2016 election, Jayalalithaa had become the chief minister and served for almost six months before she died. Upon her death, O. Panneerselvam took charge as the chief minister, shortly after which Edappadi K. Palaniswami was sworn in as the chief minister in 2017, and served till the end of the 15th assembly's tenure.

The DMK led the Secular Progressive Alliance (SPA), consisting of the Indian National Congress, the Communist parties and others, and named Stalin as its candidate for the chief minister's office. The AIADMK joined the National Democratic Alliance (NDA), led by the Bharatiya Janata Party, the ruling party of the Union Government of India, and projected Palanisami as its chief ministerial candidate. The polling was held with COVID-19 safety guidelines, and the state recorded a voter turnout of 73.63%. Surveys before and after the polls predicted a win for the DMK-led SPA. The votes were counted on 2 May 2021, and the SPA won 159 seats, with the DMK winning in 133 constituencies, securing an absolute majority for the first time in 25 years. The NDA won 75 seats, out of which 66 were won by the AIADMK. 11 ministers from the outgoing Palaniswami cabinet were defeated in their respective constituencies. The DMK formed the state government for the sixth time, and the M. K. Stalin ministry was sworn in on 7 May 2021.

Overview The state of Tamil Nadu is divided into 234 assembly constituencies, each of which elects a member (called an MLA) to represent it at the state's unicameral legislative assembly, as per Article 168 of the Constitution of India. The Tamil Nadu Legislative Assembly convenes at Fort St. George, Chennai. The chief ministerial candidate that receives the support of the majority of MLAs, which is a minimum of 118 members, is appointed as the Chief Minister of Tamil Nadu, who is the executive head of the Government of Tamil Nadu. The Governor of Tamil Nadu, the state's ceremonial head, will invite the Chief-Minister-elect and his Council of Ministers to be sworn in, to lead the state government for a term of the next five years.

Tamil Nadu's partisan politics have been dominated by its two regional Dravidian parties, Dravida Munnetra Kazhagam (DMK) and All India Anna Dravida Munnetra Kazhagam (AIADMK), for the last 50 years (since 1967). Each recognized party in India is given a polling symbol by the Election Commission of India, an independent and neutral body of officers that conducts and regulates all the elections in the country. The DMK contests with the Rising Sun symbol, while the AIADMK contests with the Two Leaves.

The legislative assembly of Tamil Nadu goes to polls alongside the legislative assemblies of three other Indian states, namely Assam, Kerala, and West Bengal, and that of the union territory of Puducherry.

Background

Since the death of AIADMK founder M.G Ramachandran (who had been in power since 1977) in 1987, DMK's M Karunanidhi (who came into prominence in 1969 following the death of DMK founder C.N Annadurai) & AIADMK's J Jayalalitha heavily dominated the state's politics. DMK won the 1989, 1996 & 2006 elections while AIADMK won the 1991, 2001 & 2011 elections. In 2016, AIADMK retained its majority with 136 seats, while the DMK increased its strength to 98 seats. Jayalalitha became the second incumbent Chief minister of Tamil Nadu to be re-elected back in power since MGR's re-election in 1984. 2021's election of the sixteenth assembly election is the first state election after the deaths of Jayalalithaa and Karunanidhi, who died in 2016 and 2018 respectively.

Rise and fall of V.K. Sasikala Following Jayalalithaa's demise from cardiac arrest on 5 December 2016, O. Panneerselvam of the AIADMK became the Chief Minister of Tamil Nadu for the third time. The first two times he attained the post (21 September 2001 to 2 March 2002, and 28 September 2014 to 23 May 2015) was when Jayalalithaa was forcibly removed from office twice due to the lawsuit against her. He served as the Acting Chief Minister during Jayalalithaa's hospitalization in 2016. However, soon after swearing-in, Panneerselvam rebelled against the influence of V. K. Sasikala, a long-time friend and close aide of Jayalalithaa, inside the AIADMK party, and deemed her a threat to his Chief Ministership, exposing the factionalism inside the party. In a meeting of the party's general council held on 29 December 2016, the first meeting after Jayalalithaa's death, Sasikala was appointed as the party's temporary general secretary. On 5 February 2017, all the MLAs of the AIADMK unanimously elected Sasikala as the Legislative Assembly leader of the AIADMK, making her the Chief-Minister-elect officially.

On 6 February 2017, Panneerselvam submitted his resignation letter to then Governor of Tamil Nadu, C. Vidyasagar Rao, who accepted the resignation but instructed him to continue to functioning as Chief Minister "until alternate arrangements are made", awaiting the pending verdict of the 18-year-long trial regarding the disproportionate assets of Jayalalithaa and Sasikala. Later Pannerselvam made mediation in Jayalalithaa's memorial on 7 February and he was coerced into resignation. He called it as "Dharmayudam". Later in the 9 February, Sasikala met the Governor and laid claims to the Chief Ministership, by submitting the list of AIADMK legislators who back her. Reports stated Sasikala had those MLAs sequestered at a resort in South Chennai named Koovathur.

On 14 February 2017, the Supreme Court of India pronounced Sasikala and her relatives guilty of criminally conspiring, laundering and amassing illicit wealth worth about in the 1990s, and sentenced them to serve a four-year jail term at Central Prison, Bangalore, giving the convicts 24 hours to surrender. This restored in toto her earlier conviction in the case delivered on 27 September 2014. Proceedings against Jayalalithaa had been abated and dismissed on account of her death. The conviction effectively ended Sasikala's Chief Ministerial ambitions.

Following Sasikala's conviction, the Governor rejected her claims to become the Chief Minister of Tamil Nadu. In her ticking 24-hour surrender time-limit and capacity as the general secretary of the AIADMK, Sasikala convened the party's MLAs, who unanimously elected Edappadi K. Palaniswami, a then supporter of Sasikala, as the new Chief Minister. She also appointed her nephew and former treasurer of the party, T. T. V. Dhinakaran, as the party's deputy general secretary. Palaniswami as sworn in as the Chief Minister of Tamil Nadu the next day, replacing Panneerselvam.

On 23 March 2017, the Election commission of India designated the two factions separately; Panneerselvam's faction known as "AIADMK (Puratchi Thalaivi Amma)", while Dhinakaran-Palaniswami's faction known as "AIADMK (Amma)". By-polls were announced at the Dr. Radhakrishnan Nagar constituency, which was vacated due to Jayalalithaa's death. Dhinakaran was named candidate by his faction. However, the Election Commission canceled the by-polls after evidence of large-scale bribing by the ruling AIADMK (Amma) surfaced. On 17 April 2017, Delhi Police registered a case against Dhinakaran for allegedly attempting to bribe the Election Commission into giving the AIADMK's significant Twin Leaves symbol to his faction. Dhinakaran was granted bail on the grounds that the police failed to identify the bribed officer.

In the following months, the Chief Minister had a fallout with Dhinakaran. Palaniswami pronounced Dhinakaran's appointment as deputy general secretary "invalid" on 17 August 2017, and ousted him from the party.

AIADMK under Dual Leadership On 21 August 2017, it was reported that the Paneerselvam faction of AIADMK had decided to merge back with the Palaniswami faction, under the terms that Sasikala would be expelled from the party. On 21 August 2017, both Palaniswami and Paneerselvam factions of the AIADMK reunited, with the leaders assuming co-leadership of the party. Panneerselvam sworn in as the Deputy Chief Minister of Tamil Nadu, Finance Minister of Tamil Nadu and the coordinator of the AIADMK. Palaniswami was dubbed the joint coordinator of the party. Mainstream media and publications suspected the involvement of the Bharatiya Janata Party, the ruling party of the Union Government of India, in the AIADMK's merger. This marked the first time the BJP began to play an influential role in the Tamil Nadu politics, acting as the mediator that united the two factions. Dhinakaran and his supporters continued to dub themselves the "real AIADMK".

On 22 August 2017, 18 MLAs of the AIADMK pledged allegiance to Dhinakaran and submitted letters to the Governor, expressing lack of confidence in Palaniswami and withdrawing their support to the Palaniswami-led government. Immediately, those MLAs were expelled from the AIADMK. The Speaker of the fifteenth Tamil Nadu Legislative Assembly, P. Dhanapal, also disqualified those MLAs from their offices, citing the Constitution Act of 1985, which prevents the instability caused by democratically elected representatives in India's legislatures shifting allegiance from the parties they supported at the time of election, or disobeying their parties' decisions at critical times, by rendering their seats vacant. This resulted in a long legal battle, at the end of which, the Madras High Court, the highest court of Tamil Nadu, gave a verdict in the Speaker's favour and confirmed the disqualification of the 19 legislators. Following these events, Sasikala was expelled from the party on 12 September 2017, with her position as interim general secretary disputed and abolished. Instead, the late Jayalalithaa was named the eternal general secretary of AIADMK.

On 23 November 2017, the Election Commission of India granted the Two Leaves symbol to the Palaniswami-Panneerselvam led AIADMK, authorizing the faction as the original AIADMK, and announced by-polls to the vacant seat of Radhakrishnan Nagar on 21 December 2017. Dhinakaran contested in the constituency as an independent candidate, and won the election with a huge margin, with around 40,000 votes more than his closest competitor. He became the first independent candidate in Tamil Nadu history to win a bypoll, claiming 50.32% of the total votes, defeating the ruling AIADMK and the opposition DMK.

In March 2018, Dinakaran formed the new party Amma Makkal Munnettra Kazagam (AMMK), with the goal of obtaining control of the AIADMK.

Rise of M. K. Stalin