JAKARTA -- The overflowing crowd of 200,000 gathered at Jakarta's Bung Karno Stadium roared as opposition leader Prabowo Subianto took the stage. "Up, up Prabowo-Sandi, down, down Jokowi," they sang.

Echoes of "Allahu akbar!" ("God is great") reverberated during the April 7 campaign rally, where Islamic preachers delivered fiery sermons to call on Indonesian Muslims to vote for Subianto and his running mate Sandiaga Uno, and against incumbent President Joko "Jokowi" Widodo.

In a combative speech, the former army general challenged Widodo's claims for economic growth and poverty reduction and laid into his infrastructure push, saying it had left state-owned companies debt-strapped.

"The people of Indonesia want changes. They don't want to be lied to anymore. They now demand a government that has common sense, who will work for its entire people," Subianto said, amid a chorus of approval from his white-clad supporters. "I would like to thank God Almighty for giving me the opportunity to defend my people, to fight evil, injustice and leaders who fool their own people!"

A few hours later, Widodo -- whose personal charisma on the campaign trail helped sweep him into office in 2014 -- followed up with his own rally. But the scene could not have been more different from his opponent's rollicking show.

Presidential candidate Prabowo Subianto addresses a roughly 200,000-strong crowd of supporters at a stadium rally in Jakarta on April 7. (Photo by Ken Kobayashi)

The event in Bumi Serpong Damai, a privately developed township on the outskirts of Jakarta, was aimed at drawing in young voters. Perhaps it was due to a torrential rainstorm just as the rally was set to begin, or maybe the last-minute venue change, but the president's event fell well short of the 7,000 people that had been expected.

Widodo's more sober tone failed to fire up the scant supporters that had gathered. "I am happy for all of you to come here," the president said. "There are only 10 days [until the election]. Be careful not to disband because of hoaxes, slanders, lies ... Please invite your friends, families to go to the polling station in droves."

In the final stretch ahead of Indonesia's April 17 election -- a rematch of the 2014 presidential contest -- Subianto appears to have gained momentum and chipped away at Widodo's strong lead in the polls. Perhaps most surprisingly, Subianto has made inroads with a group that strongly backed Widodo in the last election: the young.

Subianto appears to be benefiting from rising piety among some young Indonesian Muslims -- a phenomenon known as hijrah. The term, which means "migration" in Arabic, is often used to refer to born-again Muslims -- those who undergo a spiritual transformation to leave behind a secular, hedonistic or sinful lifestyle to make Islam a larger part of their life.

Among them is Anna, a 27-year-old office worker in Jakarta, who began her hijrah after the massive Muslim rallies orchestrated in late 2016 that led to the downfall of Jakarta's governor, a Chinese Christian named Basuki Tjahaja Purnama, better known as "Ahok." A key Widodo ally, he lost the Jakarta election to an opposition-backed candidate and was subsequently jailed for blasphemy.

"I sympathized with the Defend Islam Action because it shows how Muslims in Indonesia were united to defend our religion," Anna said. "I decided to do hijrah in January 2017."

Since then, she has traded in her miniskirts for a hijab, and instead of hitting the nightclubs she began to attend an Islamic study group at a local mosque. She is now very cautious with food, strictly eating halal-certified. And she is currently transferring her savings from a conventional bank to a sharia institution that complies with the teachings of Islam.

Anna is a member of Indonesia's vast group of millennials -- broadly described as those born between the early 1980s to early 2000s -- who will play an outsize role in deciding the outcome of the election. The General Elections Commission estimates that millennials represent 40% of the country's eligible voters -- a staggering 80 million people.

"Millennials form the largest age group among the voters ... they are the ones who will decide the future of Indonesia," Hasanuddin Ali, a political analyst and the chief executive of research company Alvara Research Center, said.

Young Indonesians crowd a K-pop concert in Jakarta: Millennials account for around 40% of eligible voters. (Photo by Ken Kobayashi)

This is the same voter base that helped usher Widodo into office five years ago. Seen as a fresh-faced reformer and an outsider, Widodo appealed to young people who had grown tired of old-guard politicians tied to the 32-year authoritarian regime of Suharto, which ended in 1998.

Subianto was seen then as the embodiment of that old guard. He was Suharto's son-in-law, and as a high-ranking military officer was believed to have been a major actor in the crackdown on democracy activists during the political turbulence of 1998.

Now, however, Widodo's support among Indonesians in their 20s and 30s seems to be slipping -- a possible reflection of a wider shift in attitudes among the nation's millennials.

A March survey by Litbang Kompas, a research arm for Kompas daily, showed a tight race between the two candidates among millennial voters. For those aged between 22 and 30, the gap between the candidates' approval ratings was 8.1%, and for those between 31 and 40, it was 6.9%, as opposed to the older generations among whom Widodo retains double-digit leads. Subianto even leads among first-time voters, or Generation Z.

Toto Suryaningtyas, a researcher at Litbang Kompas, said the hijrah movement among millennials has played a part in the erosion of Widodo's popularity. "This rising phenomenon of attachment to religious cultures and values ... obviously has impacts. Sermons at mosques are now often directed to support Prabowo."

He added that the same sermons often attack Widodo's policies, calling them responsible for spurring injustices and poverty.

But it would be a mistake to suggest that the surging piety among some millennials represents a broad embrace of Islamist ideology in Indonesia. A study last year by Alvara shows that 81% of Indonesia's millennial Muslims are still decidedly in favor of secular principles that undergird the Republic of Indonesia, as opposed to 19% who apparently support an Islamic caliphate.

In fact, a political party founded specifically for millennials, Partai Solidaritas Indonesia, represents the opposite side of the hijrah phenomenon. Founded in 2014 with the unusual requirement that people over 45 could not join, the party has fielded millennial candidates for the upcoming legislative elections as it calls for an end to polygamy, more protection for women's rights and an easing of the nation's harsh blasphemy laws. Several polls, however, suggest that it likely will not meet the 4% parliamentary threshold needed to secure a seat in the House.

Another Alvara study found that about 40% of respondents identified as having a nationalist-religious orientation, 36% were nationalist-oriented and 23% religious-oriented in their political views.

Figures are average of LSI Denny JA, Litbang Kompas and Alvara surveys; Litbang Kompas millennial figures take average of ”young” and ”mature” millennials; LSI Denny JA figures take midpoint of ranges for both ”millennial” and ”overall” results*LSI Denny JA defines millennials as between 17-39 years old; Litbang Kompas as between 22-40 years old; Alvara unspecified**Litbang Kompas latest survey taken Feb. 22-Mar. 5; LSI Mar. 18-26; Alvara in February

"Most of the millennial Indonesian Muslims with nationalist and nationalist-religious orientations choose the Joko Widodo [ticket]," Ali said. "The religious-oriented ones, meanwhile, are mostly in favor of Prabowo Subianto-Sandiaga Uno. For Jokowi ... the competition is tighter now to win young voters, [with] the growing piety being among one of the factors."

The "new cool"

A shift in attitudes among Indonesia's millennial generation can have huge repercussions -- not just for the presidential election but also for the direction of Southeast Asia's largest economy.

Indonesia's rising and youthful middle class is expected to catapult the country to become the world's fourth largest economy by 2050 on purchasing power parity terms, according to PwC, overtaking the likes of Japan, Russia and the U.K. Economists expect the country to reap this demographic dividend for the next 30 years -- a factor that has undoubtedly been a draw for international businesses, along with the country's secular nature and rising household incomes.

Widodo has been working hard to rekindle the magic he had with Indonesia's youth in the 2014 election, in part by identifying himself with Indonesia's "unicorns" -- new economy companies such as Go-Jek and Tokopedia that have reached valuations of over $1 billion during his time in office.

In one presidential debate, he claimed that his administration's digital economy policies had given birth to Indonesia's four unicorns. "We don't want just four unicorns, we want more new unicorns in Indonesia," Widodo said. "We've prepared a program to create 1,000 new startups and connect them with global incubators." Subianto was not able to address the topic adequately in the debate, stuttering in his response.

Analysts say the rising digital economy has contributed to job growth in Indonesia. In February, the unemployment rate hit its lowest level since 2014. Widodo has overseen a steady economic expansion, with gross domestic product growing around 5% -- faster than regional peers Thailand and Malaysia, but below the 7% he pledged to deliver in his first presidential campaign.

Yet the president's approach has not resonated with the pious millennials, who view conservative Islam as the "new cool in Indonesia," said Leonard Sebastian and Andar Nubowo in a recent study by Institut Francais des Relations Internationales' Center for Asian Studies.

The conservative shift has been fanned by a heated election campaign that has given rise to identity politics. On social media, tech-savvy celebrity preachers and their youthful followers vigorously spread religious posts across their networks.

The piety among young Indonesians has been growing gradually. Hijabs, or scarves to cover women's hair, were largely banned during the decades of the authoritarian New Order regime, but they are now ubiquitous -- to the extent that there are startup companies offering more fashionable alternatives.

Rock musicians are also getting in on the act, with movements such as the Islamic metalheads of Salam Satu Jari -- or One Finger Salute, inspired by the "oneness" of Allah -- and Punk Muslim. The recent rise in piety has also been linked to the 2016 anti-Ahok rallies -- which many born-again Muslim millennials treat as a wake-up call to their previously sleeping spirituality.

Widodo's biggest step to shore up his religious base was his choice of 76-year-old Ma'ruf Amin, a cleric who is a senior figure in Nahdlatul Ulama, Indonesia's largest Muslim group, as his running mate. Observers see the choice of Amin as proof of Widodo's growing concerns over attacks against his Muslim credentials.

Widodo was born Muslim, but since 2014 he has been subject to social-media rumor mills linking him to various anti-Islam conspiracies -- which are believed to have influenced young and old voters alike.

"Jokowi is a good man, but he's been called anti-Islam," Amin said to Islamic congregation in Banten Province in January. "That is although he has chosen a cleric as his running mate. He loves clerics, he loves Islam."

Widodo's choice of Amin may have alienated some of his more progressive voters, as well as many among Indonesia's religious minorities, who tend to support the president. Amin's drab performance in the first presidential debate, where he left Widodo to answer most of the questions, did not help to endear him to young voters either.

President Widodo attends a youth-oriented rally on the outskirts of Jakarta on April 7. The incumbent still holds a wide lead in polling. (Photo by Ken Kobayashi)

In contrast, Subianto's choice of running mate has helped his chances with younger people -- including the newly pious. Uno, a 49-year-old self-made billionaire, has attracted young people with his energetic persona, good looks and successful business background.

Uno is known to have a secular background -- many rumors have surrounded his love life -- but he seems to have undergone a hijrah himself, regularly attending the Friday prayers at mosques and even visiting the tomb of NU founder Bisri Syansuri.

His actions were, at first, seen largely as ceremonial. But the Islamist coalition behind Subianto branded him a "millennial santri," or student of an Islamic school -- a phrase tailor-made to appeal to the growing ranks of pious urban youth. It seems to be working.

"If you look at Sandi [Uno], and then you look at Ma'ruf Amin, it is a no-brainer that the [youth] especially would favor him," said Pangeran Siahaan, chief executive of Asumsi, a local media company producing millennial-targeted content. He added that younger voters have no recollection of the 1998 riots and Subianto's role in those events.

"Two issues that don't appeal to young people in Indonesia are human rights and the environment," Siahaan said. "They're most interested in economy, technology, prices and real issues relevant to their daily lives."

Polarized

With the Widodo-Amin pair seen representing Indonesia's homegrown brand of Islam and Subianto-Uno identified as close to the Islamist conservatives, the election can arguably be seen as a gauge of how the two competing strains of Islam are faring.

In September, Subianto signed a pact with the Islamists' coalition in exchange for their support of his presidential bid. The pact contains clauses such as "ready to safeguard and honor religious values ... and morality ... from destructive ideologies and lifestyles."

However, he has vehemently denied that he supports an Islamic caliphate, a hot topic since the Widodo administration's ban of Hizbut Tahrir Indonesia, one of the Islamist groups that organized the anti-Ahok rallies. At the April 7 rally, Subianto reasserted his allegiance to the secular foundation of the country.

In March, the Jakarta-based Institute for Policy Analysis of Conflict said that the Islamists' support for Subianto is actually "conditional and halfhearted."

Locals pray at Masjid Agung Al Azhar mosque, Jakarta. (Photo by Ken Kobayashi)

"But measures taken by the Jokowi administration to try to weaken, co-opt and stigmatize them as extremists have only strengthened what otherwise would be a fragile alliance," the report continued. "Their fear of a Jokowi victory is much stronger than their reservations about Prabowo."

Most political analysts say Subianto is unlikely to be able to overcome the gap between his campaign and Widodo's, despite the momentum he has gained. But some analysts say that the deepening religious divide the campaign has exposed is troublesome, whoever wins.

Sebastian and Nubowo said the campaign rhetoric may leave the winner "trapped in a political strategy that would lead Indonesia on a path of deepening Islamization of politics," which they called "a worrying trend."

"In sum," they said, "religious conservatism is on a fast track to realizing their political agenda whoever wins in the 2019 presidential election."

Nikkei staff writer Ismi Damayanti in Jakarta contributed to this story.