[3] He retained the Amarpur seat in the 2015 Bihar Legislative Assembly election, standing as the Janata Dal (United) candidate.

He was considered close to the former Union Minister Digvijay Singh and was working for the state's transport corporation in Bihar.

In the elections to Bihar Legislative Assembly in 2010 too, Manjhi was successful in winning the Amarpur constituency.

In 2015, Manjhi again contested from the Amarpur constituency and he defeated Mrinal Shekhar of Bharatiya Janata Party this time.

In 2020, due to ill health and ageing issues, he decided not to contest the elections and his son Jayant Raj was the candidate of JD(U) from Amarpur.