People turned up early to vote in Amethi where a high-profile battle was on between the Congress and the Samajwadi Party (SP).
Despite being in alliance for the 403-seat assembly polls, both parties fielded their candidates in Amethi, a Gandhi bastion.
Amita Singh, who is the Congress candidate from Amethi, is the wife of the party's Rajya Sabha member Sanjay Singh and has been a legislator in the past.
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Singh cast her vote in the first hour as polling began at 7 a.m. She told reporters that people were with her party and that she would win.
Pitted against her, is SP's Gayatri Prajapati, the "tainted" minister in the Akhilesh Yadav government against whom the Supreme Court ordered an FIR in a gang rape case.
Prajapati also cast his vote and claimed that not only would he win but also that the SP would again form the government in the state, with Akhilesh Yadav as the Chief Minister for a second term.
People made long queues in many other places like Faizabad, Bahraich, Basti, Gonda, Siddharthanagar, Sant Kabeernagar, Sultanpur and Shrawasti.
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At many places, technical snags in the electronic voting machines (EVMs) lead to delays and disruptions in the polling process.
According to officials, these technical snags were reported from booth numbers 292 in Devipatan, Labhua (203), booth numbers 51,52 and 55 in Siddharthanagar.
Over 1.84 crore voters will decide the fate of 617 candidates from 11 districts till 5 p.m. There are as many as 43 women in the fray.
Voting for Alapur seat in Ambedkar Nagar was countermanded and then deferred to March 8 due to the death of an SP candidate.
In the 2012 polls, the ruling SP bagged 37 of these 52 seats (including Alapur), the Bahujan Samaj Party three, Bharatiya Janata Party five, the Congress five and the Peace Party two.