The decision to expel was taken by the Bengal unit's secretariat -- the highest decision making body in the state -- yesterday. But it is only after available members of the Politburo meet today in Delhi and give it the nod that the decision will be announced formally.
The expelled MP however is not toeing the red tape. Ritabrata Banerjee said in Kolkata last night that someone had to bell the cat, he had done it and had no regrets.
"My fight is not with the party but a coterie," he said. "Someone had to do it. I did. And I think I did the right thing," he added.
"Of course I have been in the party for 21 years. The umblical cord is being cut and I would be lying if I said I wasn't bleeding," Mr Banerjee said.
His reference to the umblical cord being cut has drawn derision on social media. In Bengali, the umblical cord is called "nari" and lewd comments are being made about what the word means in Hindi: Women.
Among the top reasons for action against Mr Banerjee was his personal life and personal indiscretions that had led to more than one woman, including his ex-wife, to complain to the CPM about him.
"People are jealous of Ritabrata's meteoric rise in the party," said one of his supporters who did not wish to be named.
Mr Banerjee, 38, joined the CPM in 1996 as a student leader, was general secretary of the student wing, SFI, From 2008 to 2016 and was elected as a Rajya Sabha MP in 2014.
He was known to be once close to former Chief Minister Buddhadeb Bhattacharjee who later distanced himself from Mr Banerjee.
Senior leaders like Gautam Deb, a Central Committee member, backed Mr Banerjee to the hilt while others, like Md Salim of the Politburo had reservations about him.
Mr Banerjee told a Bengali news channel, "Md Salim became a Politburo member only because of a minority quota in the Politburo. How can you have quotas in the Politburo."