Sushil Modi was the Deputy Chief Minister in Nitish Kumar's last cabinet.
BJP's Tarkishore Prasad will be the new Bihar Deputy Chief Minister with Sushil Kumar Modi expected to be moved to Delhi for a post in the union cabinet, sources told NDTV on Sunday.
The MLA from Bihar's Katihar, Mr Prasad was elected the BJP's leader in the assembly a day before Nitish Kumar is set to take oath as Chief Minister for the fourth time.
"I have been given this responsibility and I will carry out the duty to the best of my ability," he told news agency ANI on his legislature party post. Asked whether he was going to be Nitish Kumar's deputy, he said, "I can't comment on it as of now."
Sushil Modi, who was the Deputy Chief Minister in Nitish Kumar's last cabinet and also the leader of BJP legislature party in Bihar before 2020 Assembly polls, said Mr Prasad was unanimously elected as the leader of BJP legislature party in Bihar.
"The BJP and the Sangh Parivar gave me so much in the political life of 40 years. I will discharge the responsibility that will be given to me. No one can take away the post of the party worker," he wrote on Twitter.
He also congratulated Bettiah MLA Renu Devi on being elected as deputy leader of BJP legislature party.
"Heartly congratulations to four-time MLA from Bettiah Renu Devi, who comes from Nonia community for being elected as deputy leader of BJP legislature party," Mr Modi tweeted
Mr Prasad and Renu Devi's names were announced at the BJP legislature party meeting in Patna during the day.
The meeting was attended by senior BJP leader and Defence Minister Rajnath Singh, the party's state in-charge Bhupendra Yadav, election in-charge Devendra Fadnavis, union minister Nityanand Rai and state party chief Sanjay Jaiswal, among others.
Sushil Kumar Modi proposed name of Mr Prasad as the party's legislature party leader which was seconded by all the newly-elected MLAs.
A political lightweight compared to Mr Modi, Mr Prasad won from Karihar assembly segment in the current assembly elections for the fourth straight term.
The 52-year-old BJP leader has risen from the ranks of Akhil Bhartiya Vidyarthi Parishad (ABVP), the student wing of BJP's ideological mentor Rashtriya Swayamsevak Sangh.
Mr Prasad has studied up to Class 12 and listed agriculture as his profession his election affidavit.
The NDA managed to return to power in Bihar in the recently held election to 243-member assembly by winning 125 seats this week.