Voting started in the five Lok Sabha seats of Araria, Jhanjharpur, Supaul, Madhepura and Khagaria at 7 am in Bihar on Tuesday morning, amid tight security, officials said.
All the seats are held by the NDA.
Over 98 lakh voters will decide the electoral fate of 54 candidates in these five seats in the third phase of Lok Sabha elections.
The BJP holds Araria, where sitting MP Pradeep Singh's has been challenged by RJD's Shahnawaz, whose late father Taslimuddin, a former Union minister, had wrested the constituency from Singhin 2014 despite the Modi wave.
The RJD is also locked in straight battles with JD(U) in Madhepura and Supaul.
In Madhepura, from where RJD chief Lalu Prasad had himself won twice, JD(U) MP Dinesh Chandra Yadav's bid to hold on to the seat is being challenged by Kumar Chandradeep, who teaches English at a college in Patna, but also happens to be the son of late Ramendra Kumar Yadav, who had been a member of both Houses in Parliament.
In adjoining Supaul, the RJD has fielded Chandrahas Choupal, its MLA from one of the two reserved assembly segments falling in the Lok Sabha constituency.
Jhanjharpur has gone to the Vikassheel Insan Party (VIP) headed by former state minister Mukesh Sahni, who belatedly joined the Mahagathbandhan and got three seats from the RJD's quota of 26, in a state where the total number is 40.
Khagaria is one seat where the contest is, primarily, between two debutants. Sitting MP Mehboob Ali Kaiser, who won the seat twice on the trot for Lok Janshakti Party of late Ram Vilas Paswan, has been denied a ticket by the latter's son Chirag.
Chirag, whose party is now known as LJP (Ram Vilas), has fielded a confidant Rajesh Verma, prompting Kaiser to join RJD. Kaiser's son Yusuf Salahuddin is the RJD MLA from Simri Bakhtiyarpur, which falls under Khagaria.
The sympathy in favour of Kaiser, who is also a former state Congress president, could boost the prospects of ally CPI(M) candidate Sanjay Kumar.