Thanhawla, who was the Congress party's Chief Minister for 10 years, had won the Serchhip seat last time by 734 votes.
BJP candidate and former minister Dr Buddha Dhan Chakma is leading by over 1,000 votes against MNF nominee R M Chakma in Tuichawng seat in south Mizoram's Lawngtlai district.
Former assembly speaker Lalchamliana of the MNF is
ahead of Cooperation Minister and the lone woman legislator Vanlalawmpuii Chawngte in Hrangturzo seat.