He held "disrespect" as the reason behind the move and said he will decide the future course of action after consulting his supporters and considering all available options.
"It's not good to remain at any place where you are not given due respect. Congress ignored and neglected me in the run up to the Lok Sabha elections," he told PTI.
As part of tie up with RJD, Madhubani seat has gone to Lalu Prasad's party, which has fielded Abdul Bari Siddiqui from there.
His son and former MLC Samir Kumar Mahaseth had contested the 2009 general elections on Congress ticket from Sitamarhi, but lost.