From the Himalayan foothills to the Thar desert, from the strife-torn northeast to the silicon valley of Bangalore in the south, 12 Indian states are going to polls on the busiest day of general elections to decide who will govern the country's 1.2 billion people.

On Thursday, the parliamentary exercise will cross the half-way mark, with 121 constituencies casting their ballot in the politically important states of Uttar Pradesh, Maharashtra and West Bengal, the Maoist hit corridor of Bihar, Chhattisgarh and Jharkhand, the Himalayan state of Jammu and Kashmir and Rajasthan.

Southern Karnataka state will see polls in all 28 constituencies. Southern Odisha, Central Madhya Pradesh and a lone constituency in Manipur will also cast their votes.

Officials had been deployed on Wednesday at thousands of polling booths where they checked voter documents in several constituencies.

"You can see that all the preparations to keep the elections fair, free, transparent and error-free are done," said District Commissioner of Doda district in Jammu and Kashmir, Mubarak Singh.

"Polling parties of 128 polling stations were dispatched yesterday and they have reached their polling stations. Today polling parties are going to 129 stations,"

Security was beefed up and paramilitary forces set up as some of the most threatened states get set to vote, including the violence-affected Jammu and Kashmir and the recently riot-hit state of Uttar Pradesh.

"Paramilitary forces are deployed at all the critical and vulnerable booths, where voters may be under threat for any reasons," said Senior Superintendent of Police of northern Moradabad district, Ashok Kumar.

BJP favoured

The election has turned into a face-off between Rahul Gandhi and Narendra Modi, who has been lauded by Indian corporate leaders and foreign companies for his business-friendly policies.

Modi is Chief Minister of Gujarat, which witnessed one of India's worst anti-Muslim riots in 2002.

Modi's Hindu nationalist Bharatiya Janata Party (BJP) opposition party and its allies are expected to win a narrow majority, defeating the ruling Congress party, in the world's largest democratic election, the latest opinion poll showed on Monday.

The BJP and its allies have until now been forecast to win the largest chunk of the 543 parliamentary seats but fall short of the 272-seat mark needed for a majority.

The Congress party, led by the Nehru-Gandhi dynasty, and its allies were forecast to win just 111 parliamentary seats in the poll.

Congress faces a struggle to be re-elected after a decade in power due to public anger over the economic slowdown, high inflation and a string of corruption scandals.

With parties having campaigned rigorously for days ahead of the commencement of polls, election officers expect to see a good turnout.

"I want all the voters to come to the booths and vote, there should be free and fair elections, they should not be prohibited by any parties or any illegal measures whatsoever. Nothing should happen," said Sub Divisional Officer of eastern Siliguri district, Deepa Priya.

PHOTO CAPTION

Indian supporters of union minister, patron for the National Conference and candidate for Srinagar's seat for the lower house of parliament in India's general election Farooq Abdullah (unseen) shout slogans and listen as he speaks during an election rally in Srinagar on April 16, 2014.

Aljazeera