Voting for the by-polls to 11 assembly seats and one Lok Sabha constituency began on Saturday amid tight security, an official said.
A total of 177 candidates, including 12 women, are in the fray. Among the prominent ones are Samajwadi Party (SP) candidate from Ferozabad Lok Sabha seat, Dimple Yadav, daughter-in-law of party supremo Mulayam Singh Yadav, Congress nominee from the Padrauna assembly seat, Mohini Devi, mother of union minister of state R P N Singh.
A total 4.9 million voters are expected to exercise their franchise at 5,616 polling stations.
The polling started at 8 am for 11 assembly seats - Lucknow West, Puwayan (Shahjahanpur), Isauli (Sultanpur), Hainsar Bazar (Sant Kabirnagar), Padrauna (Kushinagar), Kolasala (Varanasi), Rari (Jaunpur), Etawah, Bhartana (Etawah), Lalitpur, Jhansi and the lone Lok Sabha Ferozabad seat.
Lucknow West assembly seat has maximum number of 20 candidates followed by Rari in Jaunpur district and Kolasla in Varanasi district which have 18 and 17 candidates respectively.
Additional Director General (Law and Order) Brij Lal told reporters that 60 deputy superintendent of police, 180 inspectors, 2,173 sub-inspectors, 3,128 head constables, 16,800 constables and 21,770 home guards have been deputed on poll duty.
Uttar Pradesh Chief Electoral Officer Umesh Sinha said central paramilitary forces have been deployed at the polling booths along with the civil police and provincial armed constabulary (PAC) troopers to ensure free and fair polling.
"Elaborate arrangements are in place to maintain a strict vigil over the by-elections for which 2,300 digital cameras and 700 video cameras have been engaged," he added.
The by-elections is seen as a countdown for the coming 2,012 assembly elections in the state with all the political parties trying to gain political grounds.
Of the 11 assembly seats, 10 were vacated after resignation of the sitting members, while a member of Bahujan Samaj Party (BSP) died in Lalitpur.
The Padrauna seat was vacated by union minister of state R.P.N Singh after he was elected to the Lok Sabha from Kushingar.
Polling begins in West Bengal
Polling began peacefully for by-elections to 10 West Bengal assembly seats on Saturday amid heightened security, an official said.
Long queues were seen in front of various polling booths as enthusiastic voters, including women, lined up to cast their franchise.
No untoward incident has been reported so far, a police officer said soon after polling started at 8 am. It will continue till 5 pm.
Around 40 companies of paramilitary forces and state armed police have been deployed to maintain security across all 10 constituencies - Bealgachia (East), Kalchini (ST), Rajganj (SC), Sujapur, Goalpokhar, Bongaon, Contai South, Egra, Serampore and Alipore.
In view of the surcharged political atmosphere in the state, the election commission has decided to post paramilitary personnel in all the booths of the 10 constituencies.
Close circuit cameras have also been installed in some sensitive booths to monitor the situation during the polling process.
Nine seats fell vacant as the sitting MLAs were elected to the Lok Sabha, while CPI-M's popular leader Subhas Chakraborty's death necessitated by-polls to the Belgachia (East) constituency.
The CPI-M and Trinamool are contesting in five and seven seats respectively. The others have been left for the Left Front allies and the Congress.
Polling begins in Himachal Pradesh
Polling began in the two assembly constituencies of Rohru and Jawali in Himachal Pradesh on Saturday, officials said.
Voters in both the constituencies - Rohru in Shimla district and Jawali in Kangra district - were seen standing in queues outside the polling stations even before voting started at 8 am.
"The polling process has started peacefully and well in time at all the polling booths. It will continue till 5 pm," state chief electoral officer Anil Khachi said.
A total of 145,957 voters will decide the fate of eight candidates, including four independents, on both the seats. The main contest is between the opposition Congress and the ruling Bharatiya Janata Party (BJP).
While the Rohru seat fell vacant after five-time former chief minister Virbhadra Singh of the Congress was elected to the Lok Sabha, the by-poll in Jawali has been necessitated by Rajan Sushant of the BJP who also won election to parliament.
The Congress has fielded former minister Sujan Singh Pathania against BJP's Baldev Raj Chaudhary from Jawali. BJP rebel Madan Sharma is also contesting from Jawali as an independent candidate.
From Rohru, BJP has pitted Khushi Ram Balnatah against Manjit Singh of the Congress.
Congress leaders, including Steel Minister Virbhadra Singh, his wife Pratibha Singh, state chief Kaul Singh Thakur and legislative party chief Vidya Stokes campaigned for the party.
BJP leaders, including Chief Minister Prem Kumar Dhumal, former union minister Shanta Kumar and Sushant, held rallies in both the constituencies.
Chief Electoral Officer Khachi said 209 polling parties have been deployed in both the constituencies.
"In Rohru, a polling party trudged 14 km to reach the polling booth in Pandar in the interiors of Dodra Kawar," he said.
According to him, 24 and 17 polling stations have been declared as hyper sensitive in Rohru and Jawali, respectively.
The BJP had fared well in the May general elections, winning three out of the four parliamentary seats in the state.