Former Kolkata Mayor Sovan Chatterjee defected to the Bharatiya Janata Party on Wednesday. The Trinamool Congress MLA from Behala Purba Assembly constituency was considered a close aide of Chief Minister Mamata Banerjee. He was also reportedly involved in raising funds for the party.

Chatterjee joined the BJP at the party headquarters in New Delhi on Wednesday in the presence of senior West Bengal leaders Mukul Roy and Arun Singh.

“Sovan had a big contribution in making Mamata Banerjee the chief minister of Bengal,” Mukul Roy, who is also a former aide of Banerjee, said, according to the Hindustan Times. “Sovan joining the BJP is a big development in Bengal politics.”

“He will now strengthen the BJP,” Roy added, PTI reported. “Let me repeat that TMC will not even get the status of the opposition party.”

Chatterjee praised the Narendra Modi government for taking “bold steps” to strengthen the country. “There should be no negative politics at this point of time,” he said.

In November last year, Chatterjee had resigned as minister after Banerjee rebuked him for allegedly ignoring official responsibilities to focus on personal matters.

Singh claimed that several people were defecting from the TMC to the BJP because they were “impressed with the leadership of Narendra Modi and Amit Shah” and disappointed with Banerjee.

Since the Lok Sabha poll results, six TMC legislators and one each from the Congress and the Left have joined the BJP. The saffron party has been making inroads into West Bengal since the General Elections. The Trinamool Congress won just 22 out of the 42 seats in the state during the Lok Sabha elections, while the BJP won 18. The state will have Assembly elections in 2021.

Roy had claimed last month that nearly 107 MLAs in West Bengal will switch to the saffron party soon as several leaders from the ruling Trinamool Congress were fed up with the way the Mamata Banerjee-led party functions.