As the ongoing Lok Sabha polls move towards a finale, the biggest battle will take place in the seventh and last phase of the elections in Uttar Pradesh.

The final phase will put to test the popularity of Prime Minister Narendra Modi in Varanasi and the prestige of Chief Minister Yogi Adityanath in Gorakhpur.

Although there is no doubt about the result of the Varanasi Lok Sabha seat, the question is mainly about the margin of victory for the Prime Minister.

Modi had won the 2014 elections with a margin of 3.37 lakh votes against his nearest rival, Aam Aadmi Party (AAP) convenor Arvind Kejriwal.

This time Modi is facing Ajay Rai of the Congress as his main rival. Rai had forfeited his deposit in 2014

With the Modi wave abating in eastern Uttar Pradesh and caste arithmetic taking over, the Bharatiya Janata Party (BJP) is determined to increase the victory margin.

"This time Prime Minister Narendra Modi will double his margin and we are all working towards this. There should be no complacency in mobilising voters. He has changed the face of Varanasi and the development is there for all to see," said Vijay Bahadur Pathak, BJP General Secretary.

BJP President Amit Shah arrived in Varanasi on Monday evening and will station himself in the constituency for the next four days. He will meet party workers and give necessary instructions for the polling day.

He will campaign in various constituencies during the day and will return to Varanasi in the evening to take stock of the progress.

In Gorakhpur, it is Adityanath's prestige at stake. The Gorakhpur seat has been with the BJP since 1991 but in the by-election in 2018, the BJP lost the seat to Samajwadi Party (SP).

Winning back the seat from the SP is now the BJP's biggest challenge in this phase. Bhojpuri star Ravi Kishan, who is the BJP candidate from Gorakhpur, is banking solely on the popularity of Modi and Yogi to win the seat.

Adityanath, whose political future depends largely on the result of Gorakhpur and, of course, the rest of the state, has been campaigning for Ravi Kishan. He has held more than 20 election meetings in the city.

"I am here to take care of development and for entertainment, you can depend on Ravi Kishan," the Chief Minister says in his rallies. Ravi Kishan takes the cue and play to the gallery with his popular dialogues. He earns applause when he talks in Bhojpuri and says, "Zindagi jhand ba, mahagathbandhan ka moonh band ba".

The caste arithmetic in Gorakhpur, however, does not favour Ravi Kishan, a Brahmin. The Brahmin-Thakur war in the region has escalated in recent months with erstwhile mafia don and a tall Brahmin leader, Hari Shankar Tiwari, being targeted by the Adityanath government.

Tensions between the two castes have increased further after outgoing BJP MP Sharad Tripathi beat up party MLA Rakesh Baghel, a Thakur, with shoes during an official meeting.

The Congress has fielded Madhsudan Tiwari who will cut into Brahmin votes.

The SP has fielded Ram Bhual Nishad. The Nishad vote in the constituency is around 4.5 lakhs and the Nishad are upset with the BJP for denying tickets to Pravin Nishad who had won the by-elect last year and had recently joined the saffron party.

Another Nishad leader, Amrendra Nishad, had also quit the SP to join BJP but was denied a ticket.

Muslims in the constituency are about 3.5 lakhs and Dalits have a population of 3 lakhs.

With the BSP supporting the SP candidate and Muslim consolidation against the BJP, the road for the BJP is not exactly smooth.

The constituencies that will go to the polls on May 19 are Varanasi, Gorakhpur, Maharajganj, Kushi Nagar, Deoria, Bansgaon, Ghosi, Salempur, Ballia, Ghazipur, Chandauli, Mirzapur and Robertsganj.