Mitra, Editor and Managing Director of The Pioneer newspaper, quit the Bharatiya Janata Party earlier this week.
Trinamool Congress secretary general Partha Chatterjee announced Mitra's switch to the Trinamool from the dais of the hugely attended rally in central Kolkata.
Mitra was nominated as a member of the Rajya Sabha in August 2003. He was elected for another term in the Upper House as a BJP MP from Madhya Pradesh in June 2010.
He unsuccessfully contested the 2014 Lok Sabha elections on the BJP ticket from Hooghly constituency in West Bengal.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
