Bengaluru, March 21 : The exit of a senior BJP leader from Kalyan Karnataka region is perceived to be a major setback for ruling BJP in the state ahead of polls. Experts say that it is a blow to BJP which will have its effect on the party in at least 20 to 30 assembly seats. Baburao Chinchanasur, is a prominent leader from Koli community in the state and played a crucial role in the defeat of AICC President Mallikarjun Kharge in the last Lok Sabha elections. He is all set to join the Congress party. The ruling BJP was hoping to win in more than 30 seats of the total 40 from Kalyan Karnataka region. However, now the party's calculations have gone wrong. The Koli voters, who supported BJP in the last assembly and parliamentary elections and have a considerable influence in the region are believed to switch their loyalty to Congress. BJP MLC Baburao had already submitted resignation to his post to the Speaker Basavaraj Horatti and was likely to join Congress officially at the Congress headquarters in Bengaluru on Tuesday. Sources close to him state that Baburao was disheartened after he was not allowed to meet Prime Minister Narendra Modi during his recent visit to Karnataka. His supporters also expressed their unhappiness over Chief Minister Basavaraj Bommai criticising him and his plea to include Koli community to ST group didn't materialise. Though, last minute compromise deals were made, Baburao had taken a call to join Congress. Sources explain that he had been offered to contest from Gurumathakal constituency. Baburao, recently challenged that he would ensure the defeat of Priyank Kharge, son of Mallikarjun Kharge in the elections. Now, the heat has been turned on BJP. Mallikarjun Kharge will have an upper hand in the region by pulling prominent leaders from the Koli community. It will also make his son Priyank Kharge contest from Chittapur a cake walk. The BJP will face a challenging situation in the entire region. Sources close to Kharge explain that he is all set to avenge his humiliating defeat in the Lok Sabha elections by giving a blow to BJP in the entire region. /IANS