He has been upset with the BJP after it asserted that the RLSP would not be given more than two seats in the 2019 Lok Sabha election, even as it went out of way to accommodate Kumar by agreeing that the saffron party and the JD(U) would fight equal number of seats.
"Kushwaha is likely to announce his parting of ways with the BJP today. He will also quit as a Union minister," a senior RLSP leader said.
The RLSP may join hands with the opposition, which includes Lalu Prasad's RJD and the Congress.
Bihar sends 40 MPs to Lok Sabha.