Rashtriya Janata Dal leader Tejashwi Yadav on Saturday said that Prime Minister Narendra Modi is a "factory, manufacturer, whole-seller, and distributor" of lies.
Tejashwi Yadav was speaking at Mamata Banerjee's mega rally in Kolkata.
He also said, "Bihari log toh udti chidya ko haldi lagaana tak jaante hain [People from Bihar can do unimaginable things]."
Mr Yadav also warned PM Modi that the thanedar (public) will ensure that no mistake goes unpunished. "Agar galti karoge, to thanedar apko saza dega (if you commit a mistake, the public would punish you)," he said.
Tejashwi further said Modi would lose sleep after the rally in Kolkata, while putting emphasis on the significance of the "mahagathbandhan".
"People who question the mahagathbandhan, let me remind them India means unity in diversity," Tejashwi said.
The mega rally organised by the TMC is being seen as a first step towards the formation of a coalition against the BJP ahead of the 2019 Lok Sabha polls.
More than 20 national leaders, including former prime minister HD Deve Gowda, his son and Karnataka Chief Minister HD Kumaraswamy, Andhra Pradesh Chief Minister N Chandrababu Naidu, Sharad Pawar, Farooq Abdullah, Sharad Yadav, Akhilesh Yadav, Tejashwi Yadav, Hemant Soren and former Arunachal Pradesh chief minister Gegong Apang, took part in the rally.
(With inputs from agencies)