Former finance minister Yashwant Sinha joined Trinamool Congress on March 13 ahead of West Bengal Assembly elections.
Sinha joined TMC in the presence of Sudip Bandyopadhyay and Derek O'Brien.
He was finance minister in Atal Bihari Vajpayee's government.
West Bengal will go to Assembly polls in eight phases starting from March 27.
Counting of votes will be held on May 02.