The All India Trinamool Congress (, ), or simply referred to as the Trinamool Congress (; ), initially named West Bengal Trinamool Congress, is an Indian political party based in the state of West Bengal founded by Mamata Banerjee in 1998.
AITC began as a breakaway faction of the Indian National Congress and rapidly rose to prominence in the politics of West Bengal under Banerjee's leadership. AITC ruled the state of West Bengal with Banerjee serving as chief minister from 2011 until 2026. The party first came to rule the state after defeating the Left Front in 2011 elections. Subsequently, the party won in 2016 and 2021 elections. However, it failed to gain majority in 2026 election, and was defeated by the Bharatiya Janata Party (BJP). After a rebellion within the party, the name and symbol of the party was frozen. Three factions emerged from the rebellion, the Nationalist Citizens Party of India, Democratic Trinamool Congress, and Mamata All India Trinamool Congress.
History Founding After being a member of the Indian National Congress (INC) for over 26 years, Mamata Banerjee quit the INC and established the AITC in 1998. The official election symbol of the AITC is Jora Ghas Phul (two flowers with grass). In the 1998 Lok Sabha polls, AITC won seven seats. In the next Lok Sabha election that was held in 1999, All India Trinamool Congress won eight seats with BJP, thus increasing its tally by one. In 2000, AITC won the Kolkata Municipal Corporation elections.
The party initially joined the National Democratic Alliance (NDA), as part of the Vajpayee government, and was initially quite successful, winning seven seats in its first election in 1998. In the 2001 Vidhan Sabha elections, the AITC won 60 seats in alliance with the INC, becoming the principal opposition party. They suffered big losses in the 2004 Lok Sabha elections and the 2006 West Bengal Legislative Assembly election, and subsequently left the National Democratic Alliance (NDA).
Nandigram movement
In December 2006, the people of Nandigram were given notice by Haldia Development Authority that a major portion of Nandigram would be seized and 70,000 people evicted from their homes to make way for a chemical plant. People started a movement against this land acquisition and the AITC helped lead the movement. The Bhumi Uchchhed Pratirodh Committee ('Committee against Land Evictions'; BUPC) was formed to protest against the eviction. On 14 March 2007, the police opened fire on the protesters and killed 14 villagers and many more went missing. Many sources claimed (and the claims were supported by the Central Bureau of Investigation in its report) that armed Communist Party of India (Marxist) cadres, along with police, fired on protesters in Nandigram Many intellectuals protested in the streets and this incident gave birth to a new movement. Socialist Unity Centre of India (Communist) leader Nanda Patra led the movement. The events led to a significant backlash against the CPI(M) government, and were a major factor in the AITC's success in the elections that followed.
Post-Nandigram/Singur elections
In the 2009 Lok Sabha election, AITC won 19 seats in West Bengal, in alliance with the Congress. They subsequently became a part of Manmohan Singh's government, with Banerjee serving as Minister of Railways.
In the 2010 Kolkata municipal election, the party won 97 out of 141 seats. It also won a majority of other municipalities.
In government In the 2011 West Bengal Legislative Assembly election, the AITC-led alliance that included the INC and SUCI(C) won 227 seats in the 294-seat legislature, defeating the incumbent Left Front government which had been in power for 34 years. AITC alone won 184 seats, enabling it to govern without an alliance. Subsequently, it won a by-election in Basirhat and two Congress MLAs switched to the AITC, giving it a total of 187 seats. Banerjee, an MP at the time, had not contested the election and had to transfer to the safe seat of Bhabanipur.
On 18 September 2012, Banerjee announced her decision to withdraw support to the UPA after the AITC's demands to undo government-instituted changes including FDI in retail, increase in the price of diesel and limiting the number of subsidised cooking gas cylinders for households, were not met.
The 2014 Lok Sabha elections saw the AITC dominate the state, winning 34 out of the 42 seats. It also qualified for national party status, as the TMC had received 6% of the vote from five different states (West Bengal, Manipur, Tripura, Jharkhand and Assam). On 2 September 2016, the Election Commission recognised AITC as a national political party.
The party was reelected in the 2016 election to a supermajority government, and Banerjee continued as chief minister.
The party won the most seats in West Bengal in the 2019 Indian general election, but suffered significant losses to the Bharatiya Janata Party, which for the first time established itself as a major force in the state. After the election, the party's status came under revision by the Election Commission of India, due to a loss in presence in most states outside West Bengal.
Banerjee's government was reelected again in the 2021 state election by an unexpectedly large margin over the BJP. Prior to the election, several high-profile AITC members such as Mukul Roy and Suvendu Adhikari had defected to the BJP. Despite the large winning margin, Banerjee was defeated by Adhikari in the Nandigram seat, where she had transferred to fight Adhikari head-on.
In the 2024 Indian general election, the AITC's campaign was led by Abhishek Banerjee and was formally part of the Indian National Developmental Inclusive Alliance. The party won 29 seats, gaining 7. In the 2026 Rajya Sabha elections, AITC nominated lawyer Menaka Guruswamy to be an MP, with her becoming India's first openly LGBTQ+ national-level member of Parliament.
2026 electoral defeat and subsequent split
In May 2026, Banerjee led the party into the 2026 West Bengal Legislative Assembly election, seeking a fourth consecutive mandate. However, her party faced a landslide defeat to the BJP, losing 135 seats. Banerjee herself was defeated by the new Chief Minister Adhikari in Bhabanipur. In a move unprecedented in Indian politics, outgoing Chief Minister Mamata Banerjee refused to resign her office despite losing her seat and a majority in the assembly as a result of the election, alleging irregularities in its conduct. She vacated the office upon the dissolution of the assembly by the governor at the end of its term on 7 May 2026. Veteran AITC politician Sovandeb Chattopadhyay led the party in Opposition.
After the expulsion of Ritabrata Banerjee from AITC, rebel group MLAs joined with Ritabrata and made a split in the party from Mamata Banerjee leadership. On 3 June 2026, 60 rebel MLAs signed a letter who accepting Ritabrata as their Leader of Opposition of the West Bengal Legislative Assembly and met West Bengal Governor to claim majority in AITC.
In June 2026, after the defeat in legislative election, 20 AITC Lok Sabha MPs including Yusuf Pathan, Saayoni Ghosh, Shatrughan Sinha, Bapi Halder, Mala Roy, Mitali Bag, Deepak Adhikari, Arup Chakraborty, Sharmila Sarkar, Satabdi Roy, Rachna Banerjee, Prasun Banerjee and others declared rebellion in the party and presented their written wish to join National Democratic Alliance. This group was led by Kakoli Ghosh.
The total strength of AITC in Lok Sabha was 28, 20 MPs therefore are eligible for splitting from the party, as per Indian anti-defection laws.
Presence in different states
North-East India Arunachal Pradesh: In the 2009 Arunachal Pradesh Legislative Assembly election, Trinamool Congress won five seats and got 15.04% of the total votes. In 2020, an Independent MLA Chakat Aboh joined the TMC.
Assam: In the 2001 Assam Legislative Assembly election, Jamal Uddin Ahmed won Badarpur constituency. He was an All India Trinamool Congress candidate. All-India president of Congress's women's wing and its national spokesperson and former Silchar MP Sushmita Dev joined the Trinamool Congress in August 2021, and remained the president of Assam unit of the party till 2026, when she joined the BJP.
Outside North-East India Goa: The All India Trinamool Congress made their state debut in the 2012 assembly election. With the 2022 Goa Legislative Assembly election approaching, the work of organising the party started from September 2021. The work began with the participation of seven-time Goa Chief Minister Luizinho Faleiro. MLA Churchill Alemao joined AITC in the same year. In the 2022 Goa Legislative Assembly Election, it got 5.2% votes.
Kerala Kerala Pradesh All India Trinamool Congress was launched in 2009. In 2014, its candidates contested five seats under the party symbol in the parliamentary election. In the 2016 state election, AITC contested in 70 assembly constituencies but due to technical errors, the party symbol was not accepted. The All India Trinamool Congress is aligned with the India Front and the UDF in the state. Democratic Movement of Kerala (DMK) was merged into the All India Trinamool Congress.
Manipur In the 2012 assembly elections of Manipur, the party won eight seats and got 10% of the total votes. It became the only opposition party in the Manipur Legislative Assembly. In the 2017 assembly elections, the party won only one seat (from Thanga) and received 5.4% of the total votes cast in the elections. Its lone member of the Manipur Legislative Assembly, Tongbram Robindro Singh, switched to the BJP in 2017.
Meghalaya AITC candidate Purno Agitok Sangma won the Tura constituency by a huge margin in the 2004 Lok Sabha election. On 24 November 2021, former Chief Minister of Meghalaya Mukul Sangma along with other 11 MLAs of INC joined AITC, which made AITC the largest opposition party in Meghalaya Legislative Assembly. In 2022, one defected MLA who has earlier switched from INC quit the party and joined BJP. In the 2023 Meghalaya Legislative Assembly election, the All India Trinamool Congress led by Mukul Sangma contested 56 of the 60 seats and won five seats and received 13.32% of the votes; as such, it became a State Party. Since 2024, it is the largest opposition in Meghalaya.
Mizoram In 2023, an Independent MLA K. Beichhua joined the AITC.
Tripura Under the leadership of Sudip Roy Barman, former leader of opposition and then MLA of Tripura, all six MLAs of the Indian National Congress defected to the AITC in 2016. Later, Barman defected to the BJP along with all of the other AITC MLAs.
AITC won one seat in Ambassa Municipal council in the 2021 Tripura civic polls. AITC emerged as the second largest party in terms of vote-share in the 120 seats it contested out of 334 seats as it garnered 19.9% of the votes in those seats.
Uttar Pradesh In 2012, Shyam Sunder Sharma contested the by-poll to Mant constituency and won on an AITC ticket. He later defected to BSP.
Electoral performance General election results Year Lok Sabha Party leader Seatscontested Seats won Seats +/- Vote %(in whole country) Vote swing Ref. 1998 12th Lok Sabha Mamata Banerjee 29 7 2.42% 1999 13th Lok Sabha 29 1 2.57% 0.15% 2004 14th Lok Sabha 33 6 2.07% 0.5% 2009 15th Lok Sabha 26 17 3.20% 1.15% 2014 16th Lok Sabha 131 15 3.84% 0.64% 2019 17th Lok Sabha 62 12 4.11% 0.27% 202418th Lok Sabha47 7 4.37% 0.26%
State Legislative Assembly elections