He defeated the Indian National Congress candidate, Ramesh Chandra Phukan, by 17333 votes.

[6] On 14 July 2014 he resigned as president of Asom Gana Parishad after its failure to get any seat in the 2014 Lok Sabha elections.

[7] AGP candidates secured a notable victory in December 1985, Mahanta who was one of those people, became the Chief Minister, he became the youngest person in the country to hold such a high office.

His first administration, however, was beset by allegations of corruption and problems of escalating violence linked to the United Liberation Front of Assam (a militant separatist group in the state).

Despite the allegations of secret killings he organized against families of ULFA members, documented in the report by the Saikia Commission to the Assam Assembly, Mahanta was missed from political leadership in the state.

In a 2010 interview on NDTV's Walk the Talk with Shekhar Gupta, editor-in-chief of The Indian Express, Mahanta said: "For the sake of the integrity and security of India, we are ready to take any blame.

"[8]In the same interview, he said that unknown agencies of the Congress Party had conspired in massacres during the Assam Movement in the early eighties.

He was also admitted to Guwahati hospital on 16 January 2021 after he complained about chest pain and high blood pressure.

Prime Minister Narendra Modi met his wife and his son and wished Mahanta a speedy recovery.