Kolkata, March 2 : In a major setback to the Trinamool Congress in West Bengal, the Left Front-backed Congress won the bypoll to the Sagardighi Assembly constituency in Murshidabad district, considered a stronghold of the ruling party. The Congress' Bayron Biswas defeated Debasish Bandopadhyay of the Trinamool by a margin of 22,980 votes. The BJP's Dilip Saha finished third. The bypoll was necessitated by the death of three-time Trinamool MLA and state minister Subrata Saha in December last year. The Congress's victory in the bypoll is significant on multiple counts. Just 22 months back in the 2021 West Bengal assembly elections, the Trinamool Congress's Subrata Saha was elected by a massive margin of 50,216 votes defeating the BJP's Mafuja Khatun. In that electoral battle, despite having a similar alliance with the Left Front, the Congress's SKM Hasanuzzaman finished in the third position securing just 36,344 votes. Subrata Saha's sudden demise in December last year necessitated the by polls at Sagardighi. Secondly, since 2011 when the Trinamool Congress came to power in West Bengal ousting the 34-year-long Left Front regime, Sagardighi had been a Trinamool Congress fort, from where the party candidates were elected by comfortable margins in three successive polls in 2011, 2016 and 2021. What is of major concern for the Trinamool Congress because of the loss in the predominantly minority-dominated Sagardighi constituency is a signal of the beginning of the erosion of the ruling party's minority vote bank, which till 2021 had provided unstinted support to Mamata Banerjee's party. Despite accepting the defeat at Sagardighi, the chief minister told media persons on Thursday afternoon that her party had been defeated by an "unethical" alliance. "Officially, the Congress and Left Front were in alliance at Sagardighi, but unofficially the BJP was also a part of the alliance. The common goal of the BJP, Congress and the Left Front was to defeat the Trinamool Congress at any cost. However, our struggle against such an unholy nexus will continue and the people of West Bengal will give them a fitting reply in the coming days," she said. With this victory the Congress marks its entry into the current state assembly, as in the 2021 polls despite having an alliance both the Left Front and the Congress ended up without any representative. Currently the only representative of the Congress-Left Front-All India Secular Front alliance in the assembly is the AISF legislator from the Bhangar assembly constituency in South 24 Parganas district, Naushad Siddique. Reacting to the victory, state Congress president Adhir Ranjan Chowdhury said that Sagardighi has proved that a proper and well-tuned alliance, along with a free and fair election can ensure the Trinamool Congress' defeat. "This victory will strengthen the Left Front-Congress alliance in the coming days and we will together fight the BJP and the Trinamool Congress in the polls," he said. /IANS