"Thank you, Nitish Kumar. My best wishes to you to retain the chair of Chief Minister of Bihar. God bless you," Kishor said in a tweet.
Kishor had joined the JD-U in September 2018 and was made the party's Vice President. He also played a major role in seat bargaining with the BJP in the Lok Sabha elections.
Kishor's remarks came soon after JD-U spokesperson and party General Secretary K.C. Tyagi in a statement said that "both of them have broken the party discipline, and thus they are being expelled from the primary membership of the party".
The development comes days after Kishor and Varma spoke against the party leadership over its stand on the controversial Citizenship Amendment Act (CAA) and the National Register of Citizens (NRC).
Kishor and Varma have been critical of Bihar Chief Minister Nitish Kumar for his stand on the CAA. JD-U had supported the bill both in the Loka Sabha and the Rajya Sabha.
Kishor was also instrumental in bringing the Grand Alliance comprising JD-U, Lalu Prasad-led Rashtriya Janata Dal and the Congress in power in Bihar in 2015 assembly polls.
Kishor had made the campaign for the JD-U and also got the 'Phir se Nitish' (once again Nitish Kumar) slogan song during the assembly polls in Bihar.
Ahead of the Bihar assembly polls in 2015, Kishor was instrumental in convincing the RJD and the Congress leadership to have Nitish Kumar as the Chief Ministerial candidate.
Varma, on the other hand, had recently posted a letter to Nitish Kumar on his Twitter handle, questioning Kumar's decision to ally with the BJP in Delhi, while revealing that the Bihar chief minister had in a private conversation criticised the BJP for destroying institutions and for humiliating him.
( With inputs from IANS )