Nearly 2.5 million had voted by midday on Thursday across six districts of Bihar in the third round of staggered elections to pick a new 243-member house. Police reported minor clashes.
Balloting continued briskly in 48 constituencies where men and women queued up outside thousands of polling centres, defyig calls from Maoists to boycott the elections.
The third phase will be a test for Chief Minister Nitish Kumar's claims of good governance and rule of law as well as his development plank.
Nitish Kumar's Janata Dal-United (JD-U) and his ally the Bharatiya Janata Party (BJP) hold 27 of the 48 seats.
The Rashtriya Janata Dal and Lok Janshakti Party hold 14 seats, and the Congress, the Bahujan Samaj Party and the Communist Party of India-Marxist Leninist (CPI-ML) one each. Independents hold four seats.
Thursday's polling began at 7 am. In some places, queues started forming even before the voting began.
Election officials said 22 percent of the voters had exercised their franchise till 11 a.m. Voting will close at 5 p.m., except in four Maoist-affected places where it will end at 3 p.m.
About 10.3 million eligible voters will determine the electoral fate of 785 candidates in the districts of Gopalganj, Siwan, Vaishali, Saran and East and West Champaran.
Bihar police chief Neelmani told IANS that polling was largely peaceful barring minor clashes and some moves by troublemakers to disturb balloting in a few booths.
Angry voters in over a dozen villages boycotted the elections and shouted slogans denouncing the government for not doing enough development work.
The electronic voting machines failed in some places, delaying polling.
Neelmani said unprecedented security measures had been taken to ensure a peaceful ballot.
Paramilitary forces have been deployed in 85 percent of the booths. Helicopters were used for air surveillance, he said.
The Sashastra Seema Bal sealed the India-Nepal border and the border with Uttar Pradesh.
The first two rounds of the elections took place Oct 21 and 24 for 47 and 45 seats respectively.
RJD leader and former railway minister Lalu Prasad is MP from Saran but Paswan was defeated in the last Lok Sabha election in Hajipur in Vaishali.
The heavyweights in this phase include former chief minister Rabri Devi, contesting from Raghopur in Vaishali and Sonepur in Saran district, JD-U's Birshen Patel from Vaishali and BJP's Renu Devi from Bettiah.
The next rounds of the six-phased elections will be held Nov 1, 9 and 20. Votes will be counted Nov 24.