The campaign for the by-election in Jharkhand's Tamar constituency, from where Chief Minister Shibu Soren is seeking election, ended on Saturday.
There are 15 candidates for Monday's election. Soren's key rivals are Basundhara Munda of the Janata Dal-United (JD-U) and Raja Peter of Jharkhand Party.
Soren has to get elected to the state assembly before Feb 27. He became chief minister on Aug 27 and he needs to become a legislator within six months.
The by-election was necessitated after JD-U legislator Ramesh Singh Munda was killed by Maoist rebels in July. His widow Basundhara Munda, the JD-U candidate, is confident of winning the election thanks to a sympathy wave.
Not taking chances, Soren visited Tamar almost every day after filing his nomination last month. He promised to develop the area within a year.
The Election Commission has made heavy security arrangements to ensure violence-free polling.