Thomas Maresca

Special for USA TODAY

JAKARTA, Indonesia — This week's hotly contested election for governor of this capital region is exposing the fault lines of tolerance in the world's largest Muslim-majority country.

The incumbent is a Christian of Chinese ethnicity — Basuki Tjahaja Purnama, known by his nickname, Ahok — the first non-Muslim governor of Jakarta in 50 years. He took over the post in 2014, when then-governor Joko Widodo was elected president.

Most agree Ahok has done a good job of reducing corruption, cleaning up pollution and improving infrastructure in this crowded and chaotic city of more than 10 million.

But he's currently on trial for blasphemy amid a growing backlash by hard-line Muslims fueled by the spread of fake news. He now could be forced into a runoff against one of his Muslim opponents.

Ahok’s approval rating hit 75% in some recent polls, until a wave of anti-Chinese sentiment spread on social media hobbled his campaign. Only 39% of Jakartans now say they plan to vote for him Wednesday, according to a survey by pollster Charta Politika.

The furor started in September, when Ahok commented on the campaign trail that his opponents were incorrectly using a Quran verse to claim Muslims shouldn’t vote for him. A video clip of the comment went viral, sparking massive protests in Jakarta in November and December. Ahok was charged with blasphemy in December and is standing trial with weekly hearings. If convicted, he faces up to five years in prison.

Ahok's campaign counters that the video was edited to make it appear Ahok was criticizing the Quran in order to galvanize the opposition.

"I am Muslim and I studied the Quran," said Ahok's vice campaign manager, Bambang Wclaluyo Wahab. "There is nothing wrong with what Ahok said. But they edited the video, and the pressure groups became bigger and bigger. Now they don't accept a non-Muslim to be governor."

As the world contends with the spread of fake news and its role in elections, many stories here claim to expose Chinese plots to undermine Indonesia, playing on anti-Chinese sentiment. One report claimed the country has seen an influx of 10 million workers from China, while another said Indonesia’s redesigned banknotes are meant to resemble China’s.

"Even in rural communities, people have access via WhatsApp and a lot of material is spread via smartphones and various other online forms," said Ross Tapsell, an Indonesia researcher at Australia National University College of Asia and the Pacific.

As trust in the news media declines and the use of social media rises, Tapsell said "that's how a lot of the anti-Chinese and anti-Ahok sentiment is distributed and how a lot of the pro-Islamic groups are promoting their causes."

On Saturday, more than 100,000 Muslim supporters held a rally at the Istiqlal Mosque in central Jakarta organized by the Islamic Defenders Front (FPI), a hard-line Muslim group. Some religious leaders urged the crowd to support a Muslim candidate in the election. Some militant factions carried black extremist banners, as well as Syrian and Palestinian flags, while chants of “kill Ahok” broke out in the crowd.

Muhammad Rizki, 39, who traveled several hours from the city of Bandung to attend the rally, said resistance to Ahok has brought together a variety of Muslim groups.

"Ahok insulted our faith. He is not a Muslim, but he commented about my faith," he said.

But Ahok also has supporters from the Muslim community.

On the same day as the rally, Siti Apipah, 51, a mother of seven, was at an Ahok campaign event wearing her hijab. Apipah said her family had benefited from Ahok’s policies that gave the urban poor better access to education and health care.

"I'm a Muslim but I support Ahok," she said. "He's honest and a good leader."

Apipah said hard-line Muslims had harassed her online and in person. "Some FPI people have yelled at me, called me an infidel," she said. "But I'm not afraid. I don't think they're good people."

The question now is whether Ahok will get enough support to win a majority. If no one gets more than 50% of the vote, a runoff will be held in April between the top two candidates. Ahok’s opponents are Agus Harimurti Yudhoyono, the son of former president Susilo Bambang Yudhoyono, and former education minister Anies Baswedan, who is currently polling second to Ahok. Both are Muslims.

The results of this regional election could resonate far beyond Jakarta and may be a referendum on what Indonesia will look like in the future. Nearly 90% of Indonesia is Muslim, and the population has long lived alongside Christian, Buddhist and Hindu minorities.

"If you are an opponent of Ahok, it's very difficult to defeat him," said Trisno Sutanto, the editor of an online news site, satuharapan.com.

"He's doing well. We all see the transformation of Jakarta. But the only handicaps of Ahok are that he's Chinese and Christian," he said. "The undercurrent is that we are seeing a conservative turn in our Islamic Indonesia."