It is a constitutional formality for Rawat who was an MP at the time of being sworn in as Chief Minister on February 1 this year to become a member of the state Assembly within six months of assuming charge.
Uttarakhand's Chief Electoral Officer Radha Raturi said all preparations for the bypoll are complete with adequate deployment of security personnel at the polling booths which fall in Dehradun, Almora and Pithoragarh districts.
However, Raturi said Uttarakhand has a history of holding peaceful elections.
Considered a Congress bastion, Dharchula seat was vacated by Congress MLA Harish Dhami last month to pave the way for Rawat to contest it.
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Bypolls to the Doiwala and Someshwar (reserved) seats were necessitated after sitting MLAs from there former chief minister Ramesh Pokhariyal Nishank and Ajay Tamta of the BJP respectively were elected as MPs from Haridwar and Almora constituencies.
A day ahead of the bypolls, Chief Minister Harish Rawat said he was confident of his party's victory in all the three seats.