- UP is voting for by-elections in Gorakhpur and Phulpur seats
- Polling is on in Bihar's Araria, Jehanabad and Bhabua
- The bypolls will test the SP-BSP deal in UP, JD(U)-BJP alliance in Bihar
Here is your 10-point cheatsheet on the big by-elections:
Yogi Adityanath, who represented Gorakhpur five consecutive times in the Lok Sabha before he took over as the Chief Minister last year, was among the first of vote. "I am not worried at all... Our victory margins will be as big as in 2014," said the Chief Minister, who had described the election as a dress rehearsal for the general election next year.
The Chief Minister has spear-headed the by-elections - campaigning extensively for the Upendra Dutt Shukla in Gorakhpur and Kaushalendra Patel, who has been fielded in Phulpur, the constituency vacated by Deputy Chief Minister Keshav Prasad Maurya. Mr Patel is a former mayor of Varanasi, the Lok Sabha constituency of Prime Minister Narendra Modi. The seat, once represented by former Prime Minister Jawaharlal Nehru, was won by the BJP for the first time in 2014.
The bypolls in Uttar Pradesh saw, for the first time in nearly 25 years, the coming together of arch rivals SP and BSP to arrest the BJP victory in the state. In 2014, the BJP won 71 of the state's 80 Lok Sabha seats and followed it up with a sweeping victory in last year's assembly elections. The arrangement is being seen as a test case for a broader opposition alliance ahead of the 2019 general elections.
Ms Mayawati, whose BSP has been reduced to the margins in the Lok Sabha and the assembly elections, has not fielded any candidate in the by-elections and announced that her party workers "will vote for the candidate who is best positioned to defeat the BJP". In return, she has enlisted the support of the SP in the upcoming Rajya Sabha and the legislative council elections in the state.
The Congress, which had an alliance with the SP in last year's assembly polls, is going alone this time after Akhilesh Yadav turned down its seat sharing offer. Their alliance was beaten hollow by the BJP in last year's assembly elections.
The by-polls in Bihar are seen as a referendum on Chief Minister Nitish Kumar's tie-up with the BJP, which Lalu Prasad's RJD has consistently described as backstabbing of the voters, who chose the Grand Alliance of the RJD, JD(U) and the Congress and turned down the BJP in 2015. It is also seen as a test for Tejashwi Yadav, who is leading the RJD after his father and party boss Lalu Prasad was jailed in a corruption case.
The Araria seat fell vacant due to the death of RJD strongman Mohd Taslimuddin, who wrested the seat from the BJP's Pradip Singh in 2014. The RJD fielded Taslimuddin's son Sarfaraz Alam, eyeing a chunk of the Muslim-Yadav voters who make up more than half the electorate. The BJP has fielded Mr Singh, who had finished runner-up in 2014. The constituency saw 57 per cent voting.
In Jehanabad, where assembly by-elections took place due to the death of RJD lawmaker Mundrika Singh Yadav, the RJD has fielded his son Uday Yadav. He is in a direct contest with the JD(U)'s Abhiram Sharma who won the seat in 2010, when his party was an ally of the BJP. The seat saw 50.06 per cent voting.
The Bhabua assembly seat was vacated after the death of the BJP's Anand Bhushan Pandey. The ruling alliance has fielded his wife Rinki Rani Pandey. The Congress - which fielded Shambhu Patel - is banking on the popularity of former Lok Sabha speaker and Dalit leader Meira Kumar. Bhabua, which has a chunk of Dalit voters, is an assembly segment of Sasaram, the parliamentary constituency represented earlier by Ms Kumar. About 54.03 per cent of voters voted here.
The results will be declared on March 14.