If BJP gets a little chunk of the opposition vote it will amount to further split in opposition vote share and Trinamool Congress will be the biggest beneficiary, Mukherjee told reporters on the sidelines of an event here.
"Earlier the Congress and CPI(M) were known to be opposition. If BJP takes a slice of that vote that will benefit us," the senior TMC leader said to a question about the saffron party making inroads in Bengal.
By-election will be held in Uluberia Lok Sabha and Noapara assembly seats on January 29. Panchayat polls in the state are also due this year.