Spend enough time discussing Indian politics this year and you will inevitably find yourself contemplating the chest proportions of a 68-year-old man. In Agra, the north Indian city famous for the Taj Mahal, it only took a few minutes.

“He has a 56-inch chest,” Harsh Bhagal said when asked why he supports India’s prime minister, Narendra Modi. It is a boast the Indian leader first made on the campaign trail in 2014. His opponents laughed, but five years later, 23-year-old Bhagal is preparing to cast his first vote for the Bharatiya Janata Janata party (BJP), inspired by its strongman leader.

“When Pakistan attacked us in Kashmir [in February],” he said – pausing momentarily to take a selfie of our interview – “Modi waited 13 days for the Hindu mourning period. Then he retaliated.”

Up to 900 million people, an eighth of the world’s population, will vote in India’s gargantuan elections, that start on 11 April and continue for six weeks. Their choice will be driven by local grievances, national issues, their caste or class, and rumours and misinformation shared online.

Quick guide India's election Show Hide Up to 900m Indians will vote over the next six weeks in a democratic contest that dwarfs any other. More than 11m polling officials and security personnel are involved, and for security reasons, the contest is broken down into seven phases, which allows teams of federal police — who are considered more impartial than their local counterparts — to monitor each one of the country’s 800,000 polling stations. Indian law requires that no voter should have to travel more than 2km to cast their ballot. In several famous examples, teams of voting officials and police are dispatched to remote areas to set up booths so that a single registered resident can vote. Voting machines are shuttled across the country by road in the country’s hinterland, boat in places such as the Andaman and Nicobar islands, through snow in the Himalayas, by camel in the desert of Rajastan and elephant in the Assamese jungle. Votes will be counted throughout the day on 23 May with results released at the same time, so we should know by end of day the makeup of parliament - although several days of squabbling over a coalition government could ensue if nobody has won a majority.Up to 900m Indians will vote over the next six weeks in a democratic contest that dwarfs any other. More than 11m polling officials and security personnel are involved, and for security reasons, the contest is broken down into seven phases, which allows teams of federal police — who are considered more impartial than their local counterparts — to monitor each one of the country’s 800,000 polling stations. Indian law requires that no voter should have to travel more than 2km to cast their ballot. In several famous examples, teams of voting officials and police are dispatched to remote areas to set up booths so that a single registered resident can vote. Voting machines are shuttled across the country by road in the country’s hinterland, boat in places such as the Andaman and Nicobar islands, through snow in the Himalayas, by camel in the desert of Rajastan and elephant in the Assamese jungle. Votes will be counted throughout the day on 23 May with results released at the same time, so we should know by end of day the makeup of parliament - although several days of squabbling over a coalition government could ensue if nobody has won a majority.

Above all, however, it will be a referendum on Modi, the country’s most powerful and polarising prime minister in generations.

Agra is a competitive seat in Uttar Pradesh, the most fiercely contested state in the country. With a population believed to be greater than Brazil’s, UP, as the state is known, offers 80 of the Indian parliament’s 543 seats – enough to make or break Indian governments. Modi swept it at the last election. Can he do it again? The Observer hit the campaign trail to try to find out.

The starting point was a rally in Agra late last month where the BJP was launching its state campaign in front of thousands of people, with dozens more watching from nearby rooftops.

A half dozen small cooling fans worked pointlessly to dent the heat. Snipes against Pakistan, India’s arch-rival with which it has clashed for more than half a century, raised the loudest cheers.

The chief guest was the BJP’s president, Amit Shah, who was presented on stage with a garland the audience was told weighed a mighty 51kg. “To give back to Pakistan,” roared Shah, “to fight back against terrorism, to fight corruption, you should choose our prime minister.”

Curious how the rally’s muscular rhetoric was impressing female voters, I asked a group of women in bright saris if they supported Modi. They agreed they did, but not with a conviction that withstood scrutiny.

Facebook Twitter Pinterest The Congress party leader, Priyanka Gandhi, waving at supporters during an election roadshow in Ayodhya, Uttar Pradesh. Photograph: Atul Loke/Getty Images

“We are poor people,” said one dressed in teal, who didn’t want to give her name. “A BJP lady came to our village and told us to come. We just go where people tell us. If you ask us to go somewhere, we go.”

Fighting Pakistan was fine, she said, but Modi had not delivered on what mattered to her most. “Jobs,” she said. “Our kids are educated, they’re filling out forms, but they’re not getting work. I have three daughters and a son. I have to get them married, but none has a job.”

Was she voting for Modi? “Last time we gave [our votes] to him,” she said, to murmurs of agreement among the women. “But this time we won’t.”

By the exit gate, a Modi fan dressed in the Indian tricolours wore a portrait of the Indian leader around his neck. He had scrawled on it a short paean to Modi’s chest. It simply read, “56”.

By calling some of Indian politics’ most basic tenets into question, Modi has caused an earthquake. Before him, contemporary elections were thought to be a game of assembling winning coalitions out of the country’s myriad regional and caste-based parties. No single party had won an outright parliamentary majority in three decades.

Modi’s popularity is making strange bedfellows of his opponents: political parties that have been bitter enemies for decades, such as UP’s Bahujan Samaj party and the Samajwadi party, are now forming alliances united by little else than the desire to beat him.

People who have a government job are seen with different eyes, that our daughter will be happy with this guy

Will their traditional voters stomach this? Can Modi’s party persuade Hindus to vote as a united bloc instead? Or, as Indians grow richer, will they increasingly be guided by issues, such as Modi’s promises of development, or warnings that his authoritarian style is undermining the country’s democracy?

Pradeep Chhibber, a professor at the University of California, Berkeley, believes India is in flux, and that nobody really knows. “The truth is, we don’t have a theory of the vote,” he says. “We don’t know why Indians vote the way they do. I wish we did.”

We had met a young man at the rally named Pushpender Baghel, who invited us to see him the following day. He was studying for India’s civil service exams, a notoriously gruelling series of tests demanding knowledge of topics ranging from the origins of the French revolution to the meaning of laissez-faire economics and the composition of clouds.

About 900,000 people apply each year; fewer than 900 make the cut. The reward is what young Indians and their families prize most: a secure government job.

Baghel had sequestered himself in a training academy for the past few months before the first stage of the exams in June, studying for at least 10 hours every day. He gave Modi seven marks out of 10. “Jobs have not been created as people want. Modi needs to work on this. But five years is not enough time.”

Modi sailed into office in 2014 on a wave of young voters. Baghel, 24, belongs to a generation weaned on promises that India is close to becoming a global superpower, and who have adjusted their expectations accordingly.

But India’s world-beating economic growth is increasingly focused in sectors that are creating fewer formal jobs – many times less than is required in a country where a million people turn 18 every month.

Modi was supposed to change that, promising in 2014 to create 250m jobs in a decade. In February a leaked government survey – that Modi disputes, and which his government allegedly tried to suppress – revealed unemployment has grown on his watch to the highest levels in 45 years.

And so the allure of a government job remains. “This expectation is not set by us, it’s set by our community,” Baghel said. “People who have a government job are seen with different eyes. People think they have a secure job, that our daughter will be happy with this guy.”

It was marriage more than the stable income that drove their ambition, he added. “If marriage wasn’t there, people could do what they want. They could take time to learn, to think critically, or just be on their own. But our community doesn’t permit this.

“People want a government job, so they can have prestigious marriages, and their social status can remain at top level,” he said.

After a two-hour drive from Agra, spent mostly on dirt tracks cut into wheat and potato fields that stretched to the horizon, Daujiram Raj appeared before us like a mirage in the village of Banni. His eyes were swollen and he carried a large stick. “The whole night I’ve been here, like a watchdog over my farm,” he said.

Indian farming, an industry that still provides jobs for up to 67% of the country, is in deep trouble. Incomes have fallen to their lowest point in 18 years. Burdened with debts, often on usurious terms from local moneylenders, thousands of farmers are killing themselves each year.

In Uttar Pradesh, an additional problem has lumbered into view. In 2017, in line with election promises to protect cows, the BJP started enforcing laws against their slaughter that had been on the statute books for years. This disrupted an illegal, if widely accepted, practice among farmers, including Hindu ones, of disposing of unproductive cows by selling them to Muslim-owned abattoirs. Most of those abattoirs are shut now, and old cows and bulls are being abandoned on a mass scale.

Farmers such as Raj have been forced to fence their crops and spend all night in tiny watch houses, repelling waves of bovine charges. “There are 200 cows here in this village that attack our fields at night,” he said. “We shine torches in their eyes but sometimes we have to go and shoo them off. They follow us [and] try to kill people who follow them.”

The cows have divided up Raj’s farmlands like a mafia. “Half of them will eat from this area,” he said, pointing to one side of the road, “and half will eat from other”. Turf wars are regular. “They also have their own fights when one eats from the other’s area,” he said. A few metres away, the culprits lounged in what used to be a gooseberry field. They had since denuded it, forcing its owners to pack up and leave for Agra city. About two dozen cows and bulls reclined in the dirt, chewing loudly and twitching their tails, barely raising their heads to look as Raj led us through the field.

Their imperiousness is not misplaced. The animals are revered by many Hindus as the symbol of non-violence. But some Hindus are willing to do violence to protect them. Modi’s rise has coincided with the formation of vigilante bands across north India, who have killed and wounded dozens of Muslims and low-caste Hindus accused of harming cows.

Raj and the other farmers are frustrated but fear that driving the animals out, even peacefully, might draw an armed response. “Of course the cow is a goddess for us,” Raj said. “But now they have become too much for us to handle or feed.”

Still, he adds, he will be voting for the BJP this year. “This is the problem we have in our village,” he says. “If this is sorted out, then we have no problem with the government.”

Facebook Twitter Pinterest A government programme means Pushpa Devi now has natural gas in her home, reducing her use of wood or cow dung for cooking fires. Photograph: Michael Safi/The Observer

We broke up the drive back to Agra near a village called Bamba, stopping for lunch at a farmers’ market. There, Chaudhry Khan Singh sat cross-legged, tending to a boiling pot of chai. “Nothing has improved in the past eight years,” he said. But Singh had been paying attention to the way Modi was received in foreign capitals. At home, the Indian leader emphasises his humble background as a railway tea-seller. Abroad, he plays the rock star, giving speeches to screaming stadiums full of Indian migrants in london and New York. In 2015 Modi met Barack Obama while wearing a £10,000 suit patterned with his name written over and over again.

Critics frequently raise this contradiction, but overlook the jolt of pride people such as Singh feel as they observe the overseas tours. “Whatever respect we have earned outside has been because of Modi,” he said.

Despite his glum assessment of India’s progress, Singh had personally benefited from one of Modi’s signature programmes. A few years ago, his household had its first toilet installed, as part of a national drive to reduce diseases associated with public defecation. The government says more than 90m toilets have been built under the programme. Singh was satisfied, but still smarted that a local official had made him pay a bribe to build the facility.

Listening in, Pushpa Devi, a woman with a broom in hand, said she had recently received a natural gas connection in her house. It was another unsexy Modi government programme that has nonetheless improved lives. With a gas stove, Devi said, she cooked less frequently using wood or cow dung; that meant less of the toxic indoor air pollution that kills a million Indians a year, and fewer hours searching for fuel.

We invited Devi to sit, but she declined. Out of earshot of the men at the tea stand, she explained that she was a dalit, formerly called the untouchables, India’s least socially powerful caste. She couldn’t sit on our level at a chai stall, she explained. “If I sit with you, I’m insulting you.”

Devi voted for Modi in 2014 but only because the head of her village told her to, she said. “Whatever he says, I vote.” She was voting for him again for the same reason, but not enthusiastically. “Except for the [gas] cylinders, I don’t see that he’s done anything for me. I can’t open my mouth, I can’t drink from the government water supply,” she said.

Yet on election day, her headman would lead her and others to the voting booth. “When there is an election, that time they will not say I’m untouchable,” she said. “They put me in the line with everybody else.”

Back in one of Agra’s older quarters, metal roller-doors were being slammed shut on rows of meat shops in a predominantly Muslim street. In a basement, Sami Aghai sat by a fan in a cramped office. “Muslims will vote for Congress,” he said, referring to India’s establishment party, which has produced three prime ministers and just inducted a latest family member, Priyanka Gandhi, into national politics. “We have no alternative.”

Modi’s rise has been confrontational for many Muslims. He is a lifelong adherent of the Hindu nationalist movement. Hindutva, as it is known, is a political ideology distinct from Hinduism, the faith. It emerged as part of a global wave of rightwing nationalist movements in the 1920s, and envisages Hindus as a single nation with a sacred culture that should be emphasised above all others. Consigned to the margins, in this vision, are India’s millions of minority citizens, including the almost 200-million-strong Muslim population.

Facebook Twitter Pinterest Supporters of Narendra Modi attend an election campaign rally in Meerut, Uttar Pradesh. Photograph: Adnan Abidi/Reuters

“The BJP has destroyed communal harmony in the past five years,” said Aghai, the national president of the Indian Muslim Development Council.

While Modi was the chief minister of Gujarat, the state witnessed its worst religious riots this century, when at least 1,000 people, mostly Muslims, were slaughtered. There has been no such rioting in the past five years, but individual attacks on Muslims have surged, according to a database tracking bias crimes.

India’s Muslim heritage is also being gradually undermined in myriad ways, petty and consequential. Allahabad, a city in Uttar Pradesh, was recently restored to its pre-Islamic era name, Prayagraj. Foreign dignitaries who visit the state no longer receive models of the Taj Mahal as souvenirs, because they “do not reflect Indian culture”, according to the chief minister, Yogi Adityanath – himself a Hindutva firebrand who has spent time in jail on charges of fomenting anti-Muslim violence.

Aghai flicked through the camera roll of his phone, showing pictures of Muslims and low-caste Hindus who have been lynched in the past five years. “Remember me when you vote,” was written under each photograph. “I got these on Facebook,” he said. “Whenever I go somewhere for social work, I show them these photos.”

India’s online population has doubled in the past five years to 500 million people. India is the largest market for both Facebook and WhatsApp. The proliferation of smartphones is changing every facet of Indian life, including politics, and both platforms have rolled out extensive measures to combat disinformation and fake news. But only so much can be filtered.

A woman’s dulcet voice began to play from Aghai’s phone, a menacing song that has gone viral since a militant from the disputed Kashmir region killed 40 Indian paramilitaries in February.

“The soldiers who were martyred in Pulwama were not killed by our enemies,” the sweet voice sang. “They lost their lives because someone from our own country betrayed us. Our enemies are in our own house. You keep accusing our neighbours – why don’t you kill those who are ready to stab us in the back?”

Our last stop before leaving Agra was the home of the man who the city’s politicians seek out when they want an electoral edge. “Our soul knows everything,” declared numerologist Ritu Vardhan Sharma as we sat in his cavernous living room, bare but for a table, some chairs, and an African grey parrot in the corner. “It knows what is going to happen in this world and what will happen in the future.” He motioned at a pendulum and two dowsing instruments on his table. “When we hold these, our soul gives a message to our muscles, and the muscles give the results by the instruments.”

Astrology is serious business in India, and many, including politicians, still seek the counsel of a local diviner before making decisions. “When they see me, only one question is there,” says Sharma, a burly man in flowing white Indian dress. “Am I winning or not?”

He had agreed to provide us the same service, predicting who would triumph when votes are counted on 23 May. He carefully wrote the possible seat totals for the BJP horizontally across a sheet of paper. Then he lifted the copper pendulum and shut his eyes.

For the next few minutes, Sharma entered a state of intense focus, undisturbed by our presence, nor by the pulsing beat of LMFAO’s Sexy and You Know It blaring from his daughter’s bedroom upstairs. The pendulum, which had swung wildly, began to settle and then swing determinedly towards one outcome on the sheet: a minimum 275-seat BJP majority.

Sharma was ready to make his prediction. “I can give you a guarantee that the prime minister will be Narendra Modi,” he declared. “100%.”

The people we met in Agra had not been so enthusiastic. The realities of governing have taken the sheen off Modi. But voters in Uttar Pradesh still wanted to believe in him: that an Indian leader could deliver dynamic, incorruptible government; that an ageing prime minister really could have a 56-inch chest.