Deshmukh, Minister of State for Finance, is taking on President Pratibha Patil's son Rajendrasinh Shekhawat, the official Congress candidate, in Amravati constituency of Vidarbha as an Independent.
"I have resigned from the primary membership of the party. In any case, the fact that I stayed in the poll arena meant that I could not continue being a member of Congress," Deshmukh told PTI over phone.
"I have sent a letter to MPCC President Manikrao Thakre, informing him that I am resigning from primary membership of the party," Deshmukh, seeking a consecutive third term from Amravati, said.
Meanwhile, a senior state Congress leader expressed apprehension that Deshmukh, who has been supported by the Third Front, could topple Shekhawat's applecart.