Mumbai, India (BBN)-The man who many expect to be India's next leader, Narendra Modi, will file his election nomination papers, as polling takes place in the sixth phase of general election.

Modi will file in the holy city of Varanasi, setting up an epic battle with anti-corruption campaigner Arvind Kejriwal of the Aam Aadmi Party.

Voting is scheduled in Varanasi on 12 May, the last phase of the polls.

Meanwhile, voting is taking place in 117 seats in 12 states and territories.

More than 180 million voters are eligible to vote on Thursday in an election in which the ruling Congress party is fighting the BJP.

The nine-phase vote began on 7 April and will conclude on 12 May. Votes will be counted on 16 May.

More than 814 million Indians are eligible to vote in the marathon polls.

Election Commission officials say voter turnout in most states in the general election so far has been higher than in 2009.

Over 2,000 candidates are contesting Thursday's poll across India, including the states of West Bengal, Uttar Pradesh, Madhya Pradesh, Bihar and Indian-administered Kashmir.

Thousands of police and paramilitary security personnel have been deployed at 190,935 polling stations to ensure smooth voting.

KEY BATTLEGROUND

The southern state of Tamil Nadu, where voting will be held in all 39 seats on Thursday, is a key battleground.

The main contest is between two powerful regional parties – the ruling AIADMK and the main opposition DMK.

BJP PLEDGES IMPROVED ECONOMY

The two main national parties are fringe players in the state: the BJP has stitched up a six-party alliance and hopes to put up a challenge in some constituencies, while the Congress is fighting alone.

India's financial capital, Mumbai, is also voting on Thursday in what promises to be a keenly-contested battle between two competing alliances: the ruling Congress-Nationalist Congress Party alliance is pitted against a resurgent BJP-Shiv Sena party.

In the western suburb of Bandra, people have been coming in to cast their votes since the morning, says the BBC's Yogita Limaye.

Mumbai usually doesn't see very high turnouts – it was just over 41 percent in the 2009 election – but many here say this time things might be different.

This is also an area where many Bollywood actors live and superstar Aamir Khan has already cast his vote, while Shahrukh Khan is expected to do so in the afternoon, adds our correspondent.

Indian voters crowd around polling officials to search for their names on the electoral list at a polling booth in Mumbai on April 24, 2014.

Among the star candidates whose fates will be decided by Thursday's vote are BJP leader Sushma Swaraj, social activist and anti-corruption Aam Aadmi Party's Medha Patkar, former Bollywood actress and BJP's Hema Malini and the regional Samajwadi Party leader Mulayam Singh Yadav.

The marathon vote is being staggered over five weeks for security and logistical reasons.

The main contest in the election is between the Congress, led by Rahul Gandhi, and the BJP, led by the charismatic and controversial Hindu nationalist leader Narendra Modi.

Modi, who is ahead in all the pre-election opinion polls, is the leader of Gujarat state, which witnessed one of India's worst anti-Muslim riots in 2002.

The anti-corruption Aam Aadmi (Common Man's) Party, which secured a spectacular result in local polls in Delhi last year, offers a challenge to the main parties.

Several smaller regional parties are also in the fray and if no single party wins a clear majority, they could play a crucial role in the formation of a government.

Any party or a coalition needs a minimum of 272 MPs to form a government.

POLLING DAYS

7 April – 2 states, 6 constituencies

9 April – 5 states, 7 constituencies

10 April – 14 states, 91 constituencies

12 April – 4 states, 7 constituencies

17 April – 12 states, 121 constituencies

24 April – 12 states, 117 constituencies

30 April – 9 states, 89 constituencies

7 May – 7 states, 64 constituencies

12 May – 3 states, 41 constituencies

Counting of votes – 16 May

BBN/ANS/AD/24Apr14-12:30pm (BST)