His party Mizo National Front (MNF), won from the Champhai constituency for four consecutive terms until he lost the seat in 2008 Assembly elections to the Indian National Congress (INC). He tendered his resignation to Governor MM Lakhera on 8 December 200.
Zoramthanga served as the fifth chief minister of the state.
The veteran leader started his political career in 1966 when he joined the underground movement. In 1969, he became the secretary of the president - Pu Laldenga for the next seven years.
When the Mizo National Front came to power in 1987, Zoramthanga was appointed as the in-charge of the Finance and Education Departments. He was subsequently promoted as the party's president after the death of Laldenga.
In 1998 Assembly elections, the party won the polls under the leadership of Zoramthanga, who became the chief minister of the state.