Saurabh Bharadwaj criticised Raghav Chadha for describing the AAP as a "toxic workplace" after his high-profile defection.
The AAP Delhi chief accused the former MP of conspiring against the party while planning to join the BJP under pressure.
Seven AAP Rajya Sabha MPs have officially merged with the BJP, reducing the Aam Aadmi Party's presence in the Upper House to three members.