The Mizo National Front returned to power in Mizoram after 10 years Tuesday, capturing 21 seats in the 40-member Assembly and inflicting a humiliating defeat on the Congress.
MNF is ahead in five other seats, Election Commission (EC) sources said.
With the results, the Congress has now lost power in all the seven states in the northeast.
The party which had bagged 34 seats in the 2013 Assembly elections managed to win just five seats this time.
Chief Minister Lal Thanhawla suffered defeat from both the seats he contested, including his home turf Serchip. He also lost from Champai South constituency.
Sources at the Chief Minister's Office (CMO) said Thanhawla was likely to tender his resignation to Governor Kummanam Rajasekharan around 5 pm.
The Mizo National Front (MNF) had lost power in the state in 2008.
The Zoram People's Movement (ZPM) won five seats and is ahead in three other seats.
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The Bharatiya Janata Party (BJP) opened its account in the largely-Christian dominated state as party candidate and former minister Buddha Dhan Chakma won from the Chakma-dominated Tuichawng seat in south Mizoram's Lawngtlai district.
F Lalnunmawia of the MNF defeated state Agriculture Minister K S Thanga by a margin of 2,037 votes in Aizawl South-III seat.
Former Assembly Speaker Lalchamliana of the MNF defeated the lone woman MLA and Cooperation Minister Vanlalawmpuii Chawngthu from Hrangturzo seat, while Lalrinawma of the MNF retained the
Tuikum seat by defeating Sangzela Tlau of the ruling Congress.
K Beichhua and Lalruatkima of the MNF also retained their seats--Siaha and Aizawl West-II, respectively.
Former home minister Tawnluia of MNF won from Tuichang seat, defeating his nearest ZPM rival W Chhuanawma by 701 votes.