Sadbhavana Party
He started his political career from 1990. In the 1994 parliamentary election, he stood as the Nepal Sadbhavana Party candidate in the constituency Sarlahi-2. He came second with 10173 votes. In the 1999 parliamentary election he won the seat with 14750 votes, defeating former Prime Minister Surya Bahadur Thapa of the Rastriya Prajatantra Party. In 2007, Mahato broke away from NSP(A) and formed his own party, which later acquired the name Sadbhavana Party. Mahato resigned from the interim parliament on January 19, 2008.