The former Ministers -- Kiran Walia, Yoganand Shastri, Ramakant Goswami -- have mounted an attack on Chacko and demanded his removal, accusing him of leaking a letter written by Sandeep Dikshit.
Kiran Walia said, "if Congress has to be saved in Delhi, PC Chacko should be removed."
Sources say that former Chief Minister late Sheila Dikshit's son Sandeep Dikshit had written a letter to Chacko. In the letter, Dikshit had alleged that the reason for Sheila Dikshit's death was Chacko who tortured her through letters.
She could not bear the pain and lost her life, Sandeep's letter alleged. Sources say Chacko forwarded that letter to Sonia Gandhi.
When IANS contacted Dikshit, he said it was a personal letter and only Chacko can answer why it was leaked to the media.
Chacko has resigned from the party post but was asked by Sonia Gandhi to continue till the elections.
The party is also headless since the demise of the former Chief Minister.
During the Lok Sabha elections, the Congress came second in six out of the seven Delhi seats, keeping the AAP at third position.