Trinamool Congress on Sunday officially announced Chief Minister Mamata Banerjee as its candidate for the by-election in Bhabanipur.
TMC's campaign in the seat in south Kolkata is already underway with the Election Commission announcing the bypoll on Saturday, following a request from the state government to avoid a constitutional crisis.
Banerjee, who led her party to a massive electoral triumph for a third successive term in May this year, is required to win a seat in the state assembly by November 5 in conformity with the constitutional provisions in order to continue as chief minister.
The Constitution allows a non-member of a state legislature or Parliament to continue in a ministerial position for six months.
The Bhabanipur bypoll will allow Mamata Banerjee a chance to become a member of the state legislative assembly.
Sovandeb Chattopadhyay, state cabinet minister and TMC MLA from Bhabanipur, vacated the seat to facilitate her election from there.
Banerjee had moved out of her traditional seat in Kolkata's Bhabanipur to fight in Nandigram during the Assembly polls earlier this year but lost to his former close aide Suvendu Adhikari who contested on a BJP ticket.
Bhabanipur or Bhawanipore, is Mamata's home ground, the seat from which she won the crown of Bengal in 2011, defeating the 34-year-old Left regime.
She was a six-term MP from the South Kolkata Lok Sabha seat, which has the Bhabanipur seat as one of its segments.
Polling for three "deferred adjourned" elections in two other assembly seats of West Bengal and one of Odisha will also be held the same day.
Leader of the Opposition Suvendu Adhikari said that only the EC could tell why the by-election is being held only in Bhabanipur. He also said that it was the TMC that always alleged that the poll body functions under the BJP's thumb.
(With agency inputs)