A supporter of the Indian Bharatiya Janata Party waves a flag during a speech by Prime Minister Narendra Modi in Patna on March 3. (AFP/Getty Images)

When is the election?

India’s national elections will take place in seven phases between April 11 and May 19, with results announced on May 23. Voters will elect representatives to 543 seats in Parliament, and the party with 272 or more seats will select the prime minister. If no one party or alliance wins the necessary amount of seats, parties can come together to form a coalition government.

Just how big is this exercise?

Very, very big. Held every five years, the elections are the largest democratic exercise in the world. With about 900 million eligible voters, the size of the electorate has swelled by more than 80 million compared to 2014. In that election, 550 million people ultimately cast votes.

While over 450 political parties contested the last election, only six are national parties that can claim a base of supporters across different states. The voting process will unfold at more than a million polling stations, each one overseen by a handful of election officials.

What is at stake?

This election will be pivotal to the future of India, soon to become the world’s most populous nation. India is attempting to catch up in economic terms with China, its neighbor to the east, a pursuit that requires massive investment in infrastructure and significant policy change. At the same time, the country is also deciding what kind of democracy it wants to be, having embraced a Hindu chauvinist leader by a landslide in the last national polls in 2014.

Prime Minister Narendra Modi of the Bharatiya Janata Party (BJP) came to power promising “achhe din” — good times — and development for all. While economic output has grown rapidly during his tenure, employment has not kept pace, leading to increasing numbers of jobless youth. Meanwhile, India faces a growing battle with air pollution and water shortages.

Modi’s ascent has also empowered right-wing Hindu groups. Since 2014, dozens of people have been lynched in the name of “cow protection.” Modi eventually condemned such killings.

Who are the contenders?

Modi remains the favorite to win. A native of the state of Gujarat, Modi spent much of his life within the ranks of the Rashtriya Swayamsevak Sangh, a group that seeks to make India a “Hindu nation.” In 2002, when he was chief minister of Gujarat, riots broke out that left more than 1,000 people, mostly Muslims, dead. Modi pioneered what became known as the “Gujarat model,” modernizing the state’s infrastructure and making it a favorite destination for investment.

Modi’s principal opponent is Rahul Gandhi, who heads the Indian National Congress. He is the latest member of the Nehru-Gandhi dynasty to seek to lead the country. (The family is not related to independence leader Mahatma Gandhi.) Rahul Gandhi’s great-grandfather, Jawaharlal Nehru, was India’s first prime minister. Both his grandmother, Indira Gandhi, and his father, Rajiv Gandhi, also led the country and were later assassinated. Rahul Gandhi faces an uphill battle to persuade voters to give the dynasty another try, especially after corruption scandals plagued the last Congress government.

What are the main issues?

Until recently, it appeared that employment and rural distress would be some of the main themes of the election. In January, a leaked official report showed that India’s unemployment rate had increased under the Modi government to a 45-year high. Farmers, meanwhile, have held several large marches in recent months to protest the difficult conditions they face, including rising input costs and high amounts of debt. Those issues probably contributed to defeats for the BJP in three key state elections late last year.

But that all changed on Feb. 14, when a suicide bombing in Indian-controlled Kashmir killed 40 paramilitary officers. In response, Modi launched an airstrike on an alleged militant training camp in Pakistan, setting off the most serious military confrontation between the two countries in decades. Ever since, Modi has sought to make national security the primary issue of the campaign, engaging in increasingly strident rhetoric that presents his opponents as undermining the country’s safety.

Modi is also highlighting his government’s achievements, including programs to improve the lives of poor women, a national cleanliness drive and the introduction of a new bankruptcy code.

Who pays for all this?

India’s 2019 election could be the most expensive the world has ever seen. In the last national elections in 2014, parties spent over $5 billion, according to Milan Vaishnav, director of the South Asia Program at the Carnegie Endowment for International Peace. That figure is expected to grow significantly this year. By comparison, in the 2016 presidential and congressional elections in the United States, the price tag was $6.5 billion.

In theory, there is a cap — nearly $1 million — on how much parliamentary candidates can spend on their campaign. In practice, large amounts of undeclared funds flow into candidates’ coffers.

The current government introduced two important — and controversial — changes to how campaigns are funded. Parties can now receive funds from Indians living abroad and from some foreign firms that have Indian holding companies. They can also raise money from anonymous individual or corporate donors through the use of “electoral bonds.”

What do the polls show?

In a country as large and diverse as India, polls are best taken with a grain of salt. Current opinion surveys point to Modi’s BJP winning somewhere around 228 seats, well short of the 272-seat majority mark. (In the 2014 election, the BJP won 282 seats.) However, the BJP has an alliance with other political parties, and polls indicate that the BJP-led coalition is likely to garner a slim majority in Parliament. Meanwhile, the Congress party and its allies are expected to improve their performance but still only win around 140 seats. Exit polls of actual voters will not be released until after the final phase of voting closes on May 19.

What is a “mahagathbandhan”?

A “mahagathbandhan” is a Hindi word meaning “mega-coalition” or “grand alliance.” Leaders of a variety of India’s opposition parties — among them the Congress party, the Trinamool Congress, the Aam Aadmi Party and the Samajwadi Party — have appeared together at events in recent months, raising the prospect that if they gain enough seats, they could join forces to unseat Modi and the BJP.