The Rangang-Yangang assembly constituency in Sikkim saw heavy balloting Saturday.
Election officials said nearly 73 percent of the 11,700 electors had cast their votes till 3 p.m.
Officials said no untoward incident was reported from the 14 polling stations where voting is on till 5 p.m.
The by-poll was necessitated after Chief Minister Pawan Chamling resigned from the seat and retained Namchi-Singhithang after the April assembly polls.
While the Sikkim Democratic Front (SDF) contestant is 32-year-old Kumari Manger, the Bharatiya Janata Party (BJP) has nominated 26-year-old Bikash Basnet.
Also Read
Basnet had contested in the April polls on a Sikkim Krantikari Morcha (SKM) ticket but lost by over 3,000 votes.
The SKM is not in the fray this time, and is lending support to the BJP.
Bishnu Prasad Adhikari of the Congress and Rup Narayan Chamling, Chief Minister Chamling's brother and an independent candidate, are also contesting.
