Voting began Monday morning for the by-election to the Mainpuri parliamentary and Rampur Sadar and Khatauli assembly constituencies in Uttar Pradesh, where the Samajwadi Party is locked in a high-voltage contest with the BJP.

Elaborate security arrangements have been made to ensure a free and fair polling, police said.

"Polling has started at 7 am and will continue till 6 pm," according to an official at the office of the Uttar Pradesh Chief Electoral Officer.

The bypolls are a direct contest between the ruling BJP and the opposition Samajwadi Party-Rashtriya Lok Dal (RLD) alliance. The BSP and the Congress are not contesting the seats.

In these three seats, 24.43 lakh people -- 13.14 lakh men, 11.29 lakh women and 132 third gender voters -- are eligible to exercise their franchise.

Voting is take place at 3,062 polling booths located in 1,945 polling centres.

The by-election to the Mainpuri Lok Sabha seat is taking place due to the demise of Samajwadi Party (SP) founder Mulayam Singh Yadav, while the bypolls in Rampur Sadar and Khatauli were necessitated after SP MLA Azam Khan and BJP MLA Vikram Singh Saini were disqualified following their conviction in separate cases.

While Khan was disqualified after a court awarded him three-year imprisonment in a 2019 hate speech case, Saini lost his membership of the assembly after his conviction in a 2013 Muzaffarnagar riots case.

For the Samajwadi Party, the bypolls in Mainpuri, earlier represented by its founder multiple times, and Rampur is crucial as it had lost the bypolls in June in Azamgarh and Rampur Lok Sabha seats, which were once known as its citadels.

There are six candidates in the fray in Mainpuri, 14 candidates in Khatauli and 10 in Rampur Sadar, according to the Election Commission.

In Mainpuri, Mulayam Singh Yadav's elder daughter-in-law and SP president Akhilesh Yadav's wife Dimple Yadav is pitted against BJP's Raghuraj Singh Shakya.

The BJP candidate, who was once a close associate of Pragatisheel Samajwadi Party chief and Akhilesh Yadav's uncle Shivpal Singh Yadav, joined the saffron party ahead of the Uttar Pradesh assembly polls held earlier this year.

The BJP has fielded Akash Saxena, who is the son of former party MLA Shiv Bahadur Saxena, in Rampur Sadar against senior SP leader Azam Khan's protege Asim Raja.

In Khatauli, the fight is between Vikram Singh Saini's wife Rajkumari Saini and Madan Bhaiya from the RLD.

The votes will be counted on December 8.

The outcomes of the bypolls will not have any impact on the central or the state governments as the BJP enjoys a comfortable majority at both levels. However, a win would provide a psychological advantage ahead of the 2024 parliamentary elections.