The most prominent of the battlegrounds is Amethi, a Gandhi family bastion where Congress leader Rahul Gandhi now faces two major foes: Kumar Vishwas of the AAP and Smriti Irani of the BJP.
The apparent anti-incumbency for the Congress has been compounded by an aggressive Bharatiya Janata Party (BJP), which is determined to unseat not only Gandhi in Amethi but crush all others in Uttar Pradesh.
Forty-seven of Uttar Pradesh's 80 parliamentary constituencies have already voted. After Wednesday, the last of the 18 constituencies will see polling May 12, marking the end of India's staggered elections.
Congress strategists concede the going is tough in Uttar Pradesh.
The normally straight contest in Amethi has turned triangular this time.
On Monday evening, BJP's prime ministerial candidate Narendra Modi stormed Amethi to shore up support for Smriti Irani and called upon voters to dump Rahul Gandhi, who won by over two lakh votes in 2009.
In neighbouring Pratapgarh, Congress' Raj Kumari Ratna Singh of the royal family is seeking re-election. She is up against Apna Dal-BJP combine's Kunwar Harivansh Singh, Samajwadi Party's Pramod Kumar Patel and BSP's Asif Nizamuddin Siddiqui.
In Sultanpur, once part of the Amethi constituency, BJP general secretary Varun Gandhi is the frontrunner. He faces Amita Singh of Congress and Samajwadi Party's Shakeel Ahmad.
Commando Kamal Kishore, the outgoing Congress MP from Bahraich, bordering Nepal, is pitted against BSP's Vijay Kumar, BJP's Sadhvi Savitri Bhai Phule and Samajwadi Party's Shabber Valmiki.
Union steel minister Beni Prasad Verma of Congress is contesting from Gonda. The fight here involves BJP's Kirtivardhan Singh and BSP's veteran Akbar Ahmad Dumpy also.
The Congress has fielded former criceketer Mohd Kaif in Phoolpur, once represented in the Lok Sabha by Jawaharlal Nehru. But the party machinery is not happy with him, spiking his chances of victory.
Also in the fray are outgoing BSP MP Kapil Muni Karwariya, BJP's Keshav Prasad Maurya and Samajwadi Party's Dharmraj Patel.
In Kaushambi, Samajwadi Party's Shailendra Kumar, the 2009 winner, faces BSP's Suresh Pasi, BJP's Vinod Kumar Sonkar and Congress' Mahendra Kumar.
Another crucial seat for the Congress, the Samajwadi Party and the BJP is Allahabad, home to the Nehru-Gandhi family.
The seat is held by Samajwadi Party's Reoti Raman Singh. The BJP has fielded Shyama Charan Gupta and the Congress a political turncoat Nand Lal Gupta 'Nandi'.
The Aam Aadmi Party (AAP) has fielded Adarsh Shashtri, grandson of late prime minister Lal Bahadur Shashtri.
The battles will be equally interesting in Qaiserganj, Shravasti and Faizabad, the last of which includes Ayodhya, the hub of the Ram temple movement that propelled the BJP into national limelight in the 1980s.
The other constituencies expected to see tough contests include Basti, Ambedkarnagar and Bhadohi.
A total of 2.52 crore voters will be eligible to exercise their franchise Wednesday in 25,857 polling stations.
Of the 15 Lok Sabha seats up for grabs that day, the BJP holds none, the Congress seven, the Bahujan Samaj Party five and the Samajwadi Party three.