Sushmita Dev made her anger public on February 14 this year when Rahul Gandhi announced the Congress's anti-CAA stance in Sivasagar in eastern Assam, weeks before Assembly elections.
She did not wear the gamosa (traditional Assamese towel) with anti-CAA messages written on it which Rahul and other Congress leaders in Assam wore and displayed in the massive rally organised for the elections. Sushmita was clear that the anti-CAA stand would harm the party in the Bengali-dominated Barak Valley (South Assam) having at least 15 Assembly seats.
She was also angry with Congress' alliance with Badruddin Ajmal's All India United Democratic Front (AIUDF). In early March, she offered to quit when Congress had almost decided to give seven of 15 Assembly seats to AIUDF, which would affect her fight in Silchar Lok Sabha constituency (Barak Valley) in 2024. Sonia Gandhi chipped in and made some rejig in the seat-sharing and convinced her to stay in the party.
On Sunday, Sushmita submitted her resignation to Sonia Gandhi and joined Trinamool Congress (TMC) on Monday. She flew to Kolkata and met TMC Chief and West Bengal Chief Minister Mamta Banerjee before formally joining the party.
"I cherish my three-decades-long association with Indian National Congress. May I take this opportunity to thank the party, all its leaders, workers who have been a part of my memorable journey," the letter said.
Sources said Sushmita is likely to be given "an important role" in Tripura, where TMC has set its target to wrest power from BJP in the Assembly elections slated for 2023.
Sushmita, 48, daughter of former union minister and seven-time MP Santosh Mohan Dev entered politics in 2009 and was elected as an MLA from Silchar in 2011. She was elected to Lok Sabha in 2014 from her father's constituency Silchar but lost to Rajdip Roy of BJP in 2019.
She was later made the president of All India Mahila Congress and she along with Gaurab Gogoi became two close aides of Rahul Gandhi in Assam.
"She got a lot of importance and vital responsibility in Congress. But probably, she thought, she would do better in TMC," leader of Congress legislature party in Assam, Debabrata Saikia said.
Her father was elected to Lok Sabha five times from Silchar and twice from Tripura West constituency and died in 2017. Her mother Bithika Deb was also elected as an MLA in Assam.
"TMC probably inducted her as they were looking for a Bengali leader, who can connect with BJP's Bengali vote bank," said another Congress leader.
The development came as a jolt to Congress but party workers in Barak Valley said she could not stand up to the expectations they had from the Dev family. "Unlike her father, she could not help the party win elections in the Barak Valley," a party worker said.
Barak Valley was traditionally a Congress bastion till 2014 Lok Sabha polls but Congress won only three and four Assembly seats respectively in 2016 and 2021 Assembly polls. BJP won most of the Hindu Bengali-dominated seats while AIUDF bagged the Muslim-majority seats.