Bengal Chief Minister Mamata Banerjee is all set to formally kickstart her campaign for the upcoming by-election in the eastern Indian state on Wednesday.

Mamata is contesting the crucial bypoll -- slated for September 30 -- from the assembly constituency of Bhawanipur in south Kolkata. To continue as Bengal CM, the 66-year-old has to pull off a win.

Though her Trinamool Congress party swept back to power in May's assembly polls, Mamata lost her own seat in Nandigram to her protege-turned-rival Suvendu Adhikari by around 2,000 votes. She has, however, challenged Suvendu's election in the Kolkata high court.

India's main opposition Congress has meanwhile, decided not to field any candidate against Mamata.

Also read: Mamata Banerjee sworn in as Bengal CM

"The Congress feels that by fielding a candidate against the Chief Minister, it may indirectly help the BJP in some way and the high command does not want to do that," West Bengal Congress chief Adhir Ranjan Chowdhury told the media.

On May 2, Mamata single-handedly pulled off a landslide victory in the assembly election for the third time in a row, bucking anti-incumbency and staving off a massive challenge from Prime Minister Narendra Modi's BJP.

In June, Mamata moved the high court to declare Suvendu's election win null and void on the grounds that he had indulged in corrupt practices and sought votes on the basis of religion. 

"Suvendu Adhikari has indulged in several corrupt practices that have enhanced his winning chances and materially altered Mamata Banerjee's chances of success in the election," her petition read.

Also read: Bucking anti-incumbency, Mamata scores a hat-trick in Bengal

In her petition, Mamata also alleged discrepancies in the counting of votes, Mamata's lawyer had said.

West Bengal had witnessed the most high-profile contest in India's recently held state elections. While Mamata harped on being Bengal’s daughter, the BJP asked people to vote for "change and socio-economic development" after nearly 50 years of Communist and Trinamool Congress rule.