The Election Commission has set up 1.40 lakh polling booths/stations and has made elaborate security arrangements.
Polling will be held in 17 seats in Maharashtra, 13 each in Rajasthan and Uttar Pradesh, eight in West Bengal, six each in Madhya Pradesh and Odisha, five in Bihar, three in Jharkhand and a part of the Anantnag constituency in Jammu and Kashmir.
The stakes are high for the ruling BJP and its allies as it had swept 56 of these seats in 2014, leaving just two for the Congress and the rest for other opposition parties such as the Trinamool Congress (six seats) and the Biju Janata Dal (six).
The fate of 961 candidates, including Union ministers Giriraj Singh, Subhash Bhamre, S S Ahluwalia and Babul Supriyo of the BJP and former Union ministers Salman Khurshid and Adhir Ranjan Chowdhury of the Congress, will be decided in this phase.
Among other key contestants in the fray are Kanhaiya Kumar (CPI), Baijayant Panda (BJP), Urmila Matondkar (Congress), Dimple Yadav (Samajwadi Party), Satabdi Roy (TMC) and Milind Deora (Congress).
Election in Rajasthan and Madhya Pradesh, where the BJP had cornered all but two of the total 54 seats in 2014, will begin in this phase. The Congress appeared to make a comeback, forming the governments in the states after last year's Assembly polls.
With this phase, election will come to an end in Maharashtra and Odisha.