Quick unofficial counts from Wednesday's vote, the second round of elections, suggested a decisive victory for Muslim candidate Baswedan over the Christian incumbent.
(AP Photo/Dita Alangkara). Gubernatorial candidate Anies Baswedan, center, his wife Fery Farhati Ganis, left, and daughter Mutiara show their ink-dipped fingers after giving their votes during the local election in Jakarta, Indonesia, Wednesday, April.
The early count was done by private pollsters endorsed by election officials. More than 80% of Indonesia's population professes Islam.
Blasphemy convictions in Indonesia nearly always result in conviction, and the law has been criticised by Amnesty International for hurting freedom of expression and for targeting religious minorities.
Purnama won the first round in February but not by a big enough margin to avoid a runoff.
Indonesia is the latest stop on an Asian tour by Pence that is reinforcing traditional United States alliances at a time when Donald J. Trump's presidency has raised questions about the strength of the USA commitment to the region.
Slamet Maarif, a spokesman for the Islamic Defenders Front, one of the main forces behind the push to prevent a Christian from leading Indonesia's Muslim majority capital, said the group was already eyeing the 2019 poll.
"This is a rehearsal for [the 2019 presidential election] and it sends a very clear message that if you play the Islam card it's going to help you", he said.
The thumping win by Anies Baswedan in the bitterly fought election for Jakarta governor signals twin threats to Indonesia's President Joko Widodo - from rising Islamism and the renewed clout of Indonesia's old political and business elites. Baswedan, is backed by a conservative retired general, Prabowo Subianto, who lost to Widodo in a 2014 presidential vote and may challenge him again.
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The Jakarta Post has described the campaign as "the dirtiest, most polarising and most divisive the nation has ever seen".
More than 7.1 million people are eligible to vote, and large numbers of police and military have been put on standby in the city in case of violence.
An Indonesian woman gets her finger inked at a polling station in Jakarta on April 19, 2017. Counting has begun at more than 10,000 polling booths across Indonesia's capital in a run-off election to decide who will govern Jakarta for the next five years after a campaign marred by religious tensions. One person died and more than 100 were injured after one protest turned violent.
"It is forbidden under Islamic law, to have an infidel leader", he told Reuters.
If he is found guilty, Ahok's supporters say it will be a loss for Islamic moderation that Indonesia has always been known for, and a win for fringe radical groups.
Baswedan will officially take over as governor in October.
Once considered as a political "rock star" by his opponents, Basuki "Ahok" Tjahaja Purnama now concedes defeat.
After offering his congratulations to Baswedan and his running mate - businessman and multi-millionaire Sandiago Uno, Ahok said he will continue to work hard to improve Jakarta before handing over the office in six months time. "We hope that in the future everyone can forget the campaign period". If convicted he could be sentenced to five years' imprisonment.
"As long as there are no security issues, the election outcome should not significantly stall the reform programme of the national government, in our view", Citigroup said in a note.