NEW DELHI: India, the world's largest democracy, announced Wednesday it would stage a five-week election from April 7, a contest expected to bring Hindu nationalist Narendra Modi to power on a platform of economic revival.

The head of the election commission said voting would be held in nine phases until May 12 and counting would begin four days later on May 16.

“It is expected counting will be over in a single day,” Chief Election Commissioner V.S. Sampath told a press conference.

Some 814 million people will be entitled to vote, 100 million more than in the last polls in 2009. A total of 930,000 polling stations will be set up, from the Himalayas in the north to India's tropical southern tip.

“The commission appeals to all stakeholders, and in particular the political parties and candidates, to uphold the fairness (and) democratic traditions by maintaining high standards of political discourse and fair play in the course of the campaign,” Sampath said.

The contest will pit Modi, son of a tea-stall seller, against Rahul Gandhi, the Harvard and Cambridge-educated scion of India's biggest political dynasty which has dominated post-independence politics.

After two terms of coalition government led by the leftist Congress party, the Bharatiya Janata Party (BJP) under Modi is widely forecast to emerge as the largest party.

Modi, leader of the western state of Gujarat since 2001, is seen as a pro-business reformer but his Hindu nationalism and links to anti-Muslim riots worry religious minorities and defenders of India's officially secular character.

The 63-year-old, who rose through grassroots Hindu organisations, is publicly pitching a message of jobs and development to a country struggling with decade-low economic growth and still endemic poverty.

His main opponent in the Congress is the relatively untested Gandhi, the son, grandson and great-grandson of former prime ministers who is leading the party into a national election for the first time.

Opinion polls show Modi, who was chief minister of Gujarat when anti-Muslim riots left more than 1,000 dead in 2002, holds a large advantage over his bitter rival.

But whoever emerges as the ultimate victor — and India's opinion polls are notoriously unreliable — will almost certainly have to stitch together a coalition comprising smaller regional parties.

No single party has won a parliamentary majority since 1989 and the electorate has fractured in successive decades, giving often populist regional leaders immense power at the national level.

This would likely limit any “Hindutva” or Hindu nationalist agenda which Modi attempts to put forward and could crimp his development plans.

A new movement with national ambitions, the anti-corruption Aam Aadmi (Common Man) Party led by former tax inspector Arvind Kejriwal, will also be an unpredictable element in this year's polls.

Just over a year since its formation, the party won enough seats in December's Delhi state elections to take power in what was seen as a political earthquake in the graft-plagued nation.

Congress on the slide

The Congress party under Prime Minister Manmohan Singh and its president Sonia Gandhi, the Italian-born mother of Rahul, has seen its fortunes plummet since 2009 when it won a second term in office.

Dogged by corruption scandals and sapped by slow economic growth and high inflation, its focus on new welfare programmes and social spending on the rural poor is unlikely to persuade voters to return it to power.

The 81-year-old Singh, one of India's longest-serving prime ministers, will leave office with his formerly stellar reputation based on his work as a reforming finance minister in the 1990s tarnished.

“Although it was in power for two full terms, the UPA's (coalition's) kitty of successes remains half-empty,” the Hindustan Times daily said in an editorial on Wednesday.

“Though allegations of corruption dogged the government down, it waited till the last moment to pass key anti-corruption bills, and failed.”

Formidable challenges

Rahul Gandhi's leadership credentials are also under immense scrutiny as the media-shy 43-year-old — who has never held a ministerial post — steps up as the new leader of India's top political dynasty.

The next government will inherit formidable challenges, with an economy growing at less than 5.0 per cent and the South Asian region entering a crucial period as Nato forces withdraw from Afghanistan later this year.

Afghanistan will hold presidential elections two days before the start of voting in India.

On foreign policy, a Modi-led government would be expected to take a more hardline stance on neighbouring Pakistan — the BJP has criticised attempts by Singh at peace talks — while Modi recently warned China over its “expansionist mindset”.