Indian voters will go to the polls in national elections to be held in four stages in April and May.
The Bharatiya Janata Party (BJP)-led coalition government sought early elections to capitalise on a booming economy and peace moves with Pakistan.
The polls, in which 675 million people can vote, will be held in four stages on 20 April, 26 April, 5 May and 10 May, Chief Election Commissioner TS Krishnamurthy told reporters in New Delhi on Sunday.
Opinion polls suggest the result will be a win for the BJP-led alliance by 13 May.
Parliament was dissolved on 6 February, paving the way for the polls to be held ahead of the expiry of the government's five-year term on 30 September.
The polls pit the BJP's Prime Minister Atal Behari Vajpayee, 79, against the opposition Congress Party's Italian-born leader Sonia Gandhi, 57.
The 119-year-old Congress party which led India to independence from Britain in 1947 and has ruled the country for most of its independent history is facing a crisis following its longest stint out of power.
Indian PM Atal Behari Vajpayee,
aged 79, will run in polls
Gandhi's foreign birth is a key issue in many voters' minds, polls suggest.
In a bid to appeal to the mainstream, the BJP has downplayed its Hindu revivalist roots and is hoping India's strong economic resurgence will lead to its re-election.
Since sweeping three state polls in December, the government has announced a slew of vote-grabbing economic steps and a big media campaign, titled India Shining, highlighting what it says is a "feel-good" sentiment in the country.
While pitching Vajpayee as India's "best" prime minister material and consensus builder, Deputy Prime Minister LK Advani said the BJP would seek votes based on the government's track record.
Indian Deputy PM LK Advani
says BJP has a good track record
"The coalition government led by Vajpayee has provided security and development with good governance," Advani told an election rally on Sunday in southern Karnataka state. "We are coming to you based on our accomplishments."
Congress, last in power in 1996, has pledged good governance and to preserve India's secular identity which it says the BJP has jeopardised.
It has just 109 members in the 545-seat parliament compared with the BJP's 180. Although it administers 11 of India's 28 states, it is finding it tough to prevent its support base from shrinking.
Both parties have been engaged in frantic deal-making to form broad-based alliances.
Vajpayee has also been trying to woo minorities, especially Muslims, who have shied away from the BJP due to its hardline Hindu image.
In what is likely to be a major blow to the Congress, BJP general secretary Pramod Mahajan announced that senior Congress leader Najma Heptullah, who is a prominent Muslim voice in India, would "soon" join the BJP.
Voting in the country of more than one billion people is a massive and cumbersome exercise. The current election will, for the first time, rely completely on electronic voting machines that will "ensure complete secrecy, total accuracy and neutrality", Krishnamurthy said.