The world’s largest vote has begun.

India heads to the ballot boxes today for its 16th general election, expected to be a closely fought battle and the most consequential the country has seen since the end of the Emergency years in 1977.

The process is exhausting: nine phases over six weeks, with results expected on May 16. In the mind-boggling logistical exercise, 814 million eligible voters will hit 935,000 polling stations across 28 states and seven territories, from the peaks of the Himalayas to tiny islands in the Indian Ocean, to choose 543 members of the lower house of Parliament.

The vote comes at a time when India’s economy has slowed and the country is roiling with rapid societal change, uneven development and a youthful population of 1.2 billion people who have been increasingly hitting the streets to voice their frustrations.

While no party is expected to win an outright majority, the Hindu nationalist Bharatiya Janata Party (BJP) and its leader, Narendra Modi, are leading opinion polls. The Gandhi family’s Indian National Congress party, which has dominated Indian politics since independence in 1947, appears to be facing its worst defeat ever.

Also jostling for a chunk of seats are the new anti-corruption Aam Aadmi Party (or common man party, AAP) and a recently formed “Third Front” coalition of 11 regional parties. Poll watchers are hesitant to predict how successful AAP might be, with many left red-faced after it stunned everyone by winning a substantial number of seats in Delhi’s November state election (its leader Arvind Kejriwal became Chief Minister)

A party needs to win 272 seats to rule, but in India’s increasingly fragmented Parliament, no one party has held power since 1989.

Gandhi family matriarch and Congress President Sonia Gandhi has been campaigning alongside her 43-year-old son, Rahul (pictured), the party’s expected prime ministerial candidate. But their efforts have failed to ruffle, let alone shake, the anti-incumbency mood shrouding the party after a string of corruption scandals and policy paralysis.

Congress’ manifesto — a host of welfare schemes with a right to health, pensions for the aged and disabled and the promise of inclusive development — met with an unimpressed media. The Indian Express said the 129-year-old party’s plan “warms over old welfarist promises, failing to find new appeal”.

In what is being called India’s most “presidential” elections ever, personalities have overshadowed parties, with Gujarat’s chief minister Modi, 63, and former tax official Kejriwal, 45, dominating headlines.

After failing to get anti-corruption legislation passed and resigning as Delhi’s chief minister, Kejriwal shifted his focus to the BJP and went for the jugular, contesting against Modi for the seat of Varanasi in Uttar Pradesh. The northern state is seen as crucial, with 80 seats in the lower house, and Kejriwal has been campaigning heavily there to extend AAP’s reach from Delhi. Since forming in November 2012 on the back of anti-corruption protests, AAP has become a strong alternative, amassing more than $3.7 million in donations and star candidates like Mahatma Gandhi’s grandson Rajmohan Gandhi. AAP’s main platform remains setting up an independent body to investigate corruption and decentralising power.

Modi is contesting not just from the holy city of Varanasi but Vadodara in Gujarat, playing to the aspirational middle class and business elite with a fierce pro-development platform. He remains a polarising figure, accused of having a hand in riots in which thousands of Muslims were killed in 2002. But his flashy election rallies highlight efforts to soften his image, with skullcap-adorned Muslims often positioned conveniently next to the press pen.

“Widening income disparity is fuelling tensions and the recent anti-corruption protests showed a people frustrated with the old order.”

Polls are notoriously unreliable in India, but United States think tank Pew Research Centre found 63% of Indians want BJP to win, while just 19% want Congress to return to power; 70% said they were dissatisfied and wanted political change.

Delhi-based journalist Nilanjan Mukhopadhyay met with Modi a number of times while writing his biography Narenda Modi: The Man, The Times, published last year. “I see very close similarities to him and Indira Gandhi, they have the same autocratic style, the same disregard for inner party democracy,” said Mukhopadhyay.

“If Modi gets in there will be a greater polarisation in India along religious lines …  He goes and plays on prejudice.”

Mukhopadhyay is among those who cast doubt on Modi’s much-hyped “economic miracle” in Gujarat, saying it was inherited, with the coastal state a trading hub for centuries. “Gujarat has historically always been a couple of steps further ahead than the rest of India in terms of development,” he said.

The BJP has yet to release its manifesto, but hints from Modi’s policy advisers indicate it will include plans for an overhaul of the national welfare system, massive development, bullet trains, expanding university networks, privatising state-run firms, and the reforms to bureaucracy and red-tape cutting that Modi is famous for in Gujarat. Reuters spoke to people in Modi’s camp to sniff for clues and reported: “It is clear that some of his closest advisers and campaign workers have a Thatcherite ambition for him.”

Australia reached out to Modi last August with High Commissioner to India Patrick Suckling inviting him Down Under with the enticement that “India has been on the top in Australia’s foreign policy”. Australia is also expected to be named a partner country in the state’s flashy biennial investment summit Vibrant Gujarat in 2015, although Australian officials here say it is yet to be confirmed.

Regardless of whether Modi gets India’s top job, the fact that Congress and the Gandhi family are likely on the way out has the country and Indians around the world on tenterhooks — including the roughly 450,000 in Australia.

Meghnad Desai, an Indian-born professor at the London School of Economics, says this election will be the most significant for the south Asian nation since 1977, when Congress lost power for the first time off the back of Indira Gandhi’s Emergency years, which effectively suspended democracy.

“Congress is going to lose so much that they are predicting it will go down to double-digit seats [from the 206 it now holds]; it will be very hard for it to recover from that sort of loss,” said Desai, who is also a British Labor peer. “After this election there will be a whole new configuration of the party structure … maybe the AAP will grow into an alternative to Congress as the second-largest party.”

He says people are looking for a decisive return to growth for India, whose GDP growth slowed to 4.7% in the last quarter of 2013 from nearly 9% in fiscal 2011.

India is a country witnessing rapid change. Widening income disparity is fuelling tensions and the recent anti-corruption protests showed a people frustrated with the old order. While many villages remain without power and electricity, more than half of Indians own a mobile phone.

India’s 93 million Facebook and 33 million Twitter users have seen the election battle go online for the first time in the country’s history. Meanwhile, the booming population of young people is churning out 23.2 million first-time voters. Indian elections are notoriously difficult to predict, and all these first time factors add mud to already murky water. But with the country said to be the world’s next superpower and jostling for a greater say in global politics, including a permanent seat on the UN Security Council, it will pay for everyone, not just Indians, to take note of the result.