After resigning from the chief minister post, JD(U) chief Nitish Kumar on January 28 staked claim to form new government in Bihar with BJP's support.
He submitted BJP's letter of support to Governor Rajendra Arlekar which was accepted.
Earlier, Kumar severed his party's ties with the 'mahagathbandhan' in the state and the INDIA bloc and returned to the NDA fold.
Bihar BJP chief Samrat Choudhary and party leader Vijay Kumar Sinha are expected to be the deputy chief ministers in the new government.
Meanwhile, Congress compared Nitish Kumar to a "chameleon", and said the people of the state will never forgive him for his "betrayal".
Lashing out at Kumar, Congress leader Jairam Ramesh said it is clear that a "political drama" is being created in order to divert attention from the Bharat Jodo Nyay Yatra.
He said it is clear that the prime minister and the BJP are "scared" of the Yatra being undertaken by Rahul Gandhi, which is set to enter Bihar soon.
"Nitish Kumar, who frequently changes political partners, is giving tough competition to the chameleons in changing colours," Ramesh said in a post in Hindi on X.