Think running a U.S. presidential election is hard? Consider the case of India.

From April 11 to May 19, nearly 900 million voters can participate in India’s national elections. An array of political parties, regional diversities and societal cleavages make it difficult to elect India’s Lok Sabha, the lower house of Parliament — let alone assemble a majority to govern.

Will the governing Bharatiya Janata Party (BJP) retain its Lok Sabha majority, or will it have to form a coalition? Or will the Indian National Congress, the BJP’s main opponent, gain ground? Here’s what you need to know:

1. How will India’s decentralized elections influence voting?

This time, India’s elections are a seven-phase process, spread over five weeks and across 29 states. The election will include more than 8,000 candidates competing for 543 parliamentary seats. There are seven national parties and more than 300 registered state parties, in addition to other smaller parties and independent candidates.

Parties need to successfully navigate a complex set of political rules. India uses a first-past-the-post electoral system, which can distort the allocation of seats because a small group of voters can change the outcome. In the 2014 election, the BJP polled 31 percent of the vote and won half of the seats (282 of 543 seats). The main opposition party, the Congress, claimed 19.3 percent, giving the party just 44 seats, its lowest-ever tally.

Together, the two major national parties polled just 50 percent of the popular vote. A small swing of even 3 to 4 percent of voters may have major repercussions. This means new voters, including women, the young, or new middle class, could swing the 2019 election, especially in specific states.

2. How influential are the 29 states?

The parliamentary elections are a measure of the performance of the national government, but also deliver verdicts on the performance of India’s state governments.

Parties in power in the states have not performed well in past parliamentary elections. In 2014, the BJP gained more seats from states where it was out of power. Similarly, Congress and other parties did better in states where they were out of power.

These 29 states are crucial to electoral arithmetic. National parties sometimes have little or no presence in the states. Smaller regional parties, espousing local issues, play an important role in the states and even at the center.

Here’s an example: In Uttar Pradesh, India’s most populous state, there are 80 Lok Sabha seats to be decided. Competition to the BJP comes from regional parties such as the Samajwadi Party and the Bahujan Samaj Party, which are in alliance for the 2019 election. Alliances with regional parties become a political compulsion for national parties to win a majority, especially where they have no state presence.

3. What do we know about India’s voters?

The Election Commission of India estimates that there will be 15 million new voters, most of them born after the economic reforms of 1991. These reforms ushered in a period of high growth and better prospects, especially in India’s booming IT sector. These young voters have always known high economic growth, which suggests that a recent economic slowdown in India may hurt the governing party.

Studies suggest that the economic reforms expanded the middle class from around 300 million in 2004 to more than 600 million in 2012. The middle class in India typically included a large backward caste population — people historically marginalized in India and who continue to face social, economic and educational isolation. They tended to vote for the Congress or regional parties, but 34 percent voted for the BJP in 2014 — more than those who voted for Congress.

In the 2014 general election, the middle class voted more than the poor, contributing further to the success of the BJP.

Thus far, there are no good predictions about turnout. But to many analysts, the big question is whether India’s middle class will show up and vote for BJP candidates.

Another big question is whether 2019 will be the “year of the woman” in India. Women’s turnout for Lok Sabha elections increased nearly 20 percent between 1962 and 2014, compared with only a 5 percent increase in the number of male voters.

In 2014, 65 percent of women voted, a turnout rate only 2 percent lower than male voters. Some studies suggest that women’s turnout may be higher than men’s in 2019 — and this could hurt the BJP. So far, it is not clear how most Indian women are likely to vote this year.

4. Will the BJP be able to hold its coalition together?

To win the election and form a majority, a party has to construct a political narrative and mobilize voters. The challenge is crafting a common narrative that energizes all critical groups: youth, women, middle class, rural poor and Dalits — those at the very bottom of India’s social order. And the winning party also has to bridge India’s enormous federal plurality.

The BJP has been more adept at coalition building, especially with regional parties. Though it has lost some partners, it has formed new alliances. The Congress, on the other hand, has failed to create pre-election alliances in crucial states.

In a post-election scenario, if no party wins a clear majority, the BJP may be better placed to form India’s next government. Thus, these alliances and the support of regional parties may prove to be the key.

5. Will nationalism be a uniting theme?

The February terrorist attacks in Jammu and Kashmir and subsequent hostilities between India and Pakistan introduced a new source of voter anxiety. Before these attacks, economic issues such as unemployment and farmers’ distress levels were the primary concerns for many voters.

The terrorist attacks gave the BJP an opportunity to shift the narrative toward national security — a message that resonates with a larger cross-section of voters, especially younger voters. The BJP has sought to brand Prime Minister Narendra Modi as a strong leader capable of protecting India’s future, and this may work in the BJP’s favor. Nationalism is a popular theme and taps into the fear of Pakistani-sponsored terrorism — and a popular desire for a strong nation.

David Schultz, a three-time Fulbright scholar, is a professor of political science at Hamline University in St. Paul, Minn., and author of more than 35 books and 200 articles, including “Presidential Swing States” (Lexington Books, 2018).

Manisha Madhava (M. Manisha) is an associate professor of political science at SNDT Women’s University in Mumbai. She is also the co-editor of “Indian Democracy; Problems and Prospects” (Anthem Press, 2009).