Polls closed in Indonesia on Wednesday in elections for president and parliament after a campaign across the sprawling equatorial archipelago that was dominated by economic issues but also marked by the growing influence of conservative Islam.

The eight-hour vote across a country that stretches more than 5,000 km (3,000 miles) from its western to eastern tips was both a Herculean logistical feat and testimony to the resilience of democracy two decades after authoritarianism was defeated.

President Joko Widodo, a furniture businessman who entered politics 14 years ago as a small-city mayor, is seeking re-election against former general Prabowo Subianto, whom he narrowly defeated in the last election, in 2014.

Indonesians show their inked fingers in Trumon, Southern Aceh province on Wednesday. Chaideer Mahyuddin/AFP

Most opinion polls give Widodo a double-digit lead, but the opposition says the race is much closer and Prabowo, dressed in a white shirt and a traditional peci cap, said before voting in the city of Bogor he was optimistic about winning.

Widodo, dressed in a white shirt and accompanied by First Lady Iriana Widodo, voted in the capital.

"I feel relieved," said Widodo, after casting his ballot and displaying a finger dipped in indelible ink, part of the process of avoiding fraudulent voting.

Polling stations opened at 7 a.m. (2200 GMT on Tuesday) in the east and closed at 1 p.m. (0600 GMT) in the west.

Unofficial "quick counts", based on samples from polling stations, will be released two hours after voting ends. The winning presidential candidate could be known by late on Wednesday, though official results will not come until May.

Any disputes can be taken to the Constitutional Court where a nine-judge panel will have 14 days to rule on them.

Voting delays

More than 10,000 volunteers will crowd-source election results posted at polling stations in a real-time bid to thwart attempts at fraud.

However, the opposition has already alleged voter list irregularities that could affect millions and has vowed legal or "people power" action if its concerns are ignored.

Widodo’s running mate, Muslim cleric Ma'ruf Amin, called a for a peaceful vote.

"The presidential election is not a war, but a search for the best leader," Kompas TV cited him as saying.

The election is being billed as the world's biggest single-day vote and is certainly one of the most complicated, with voters contending with five paper ballots for president, vice president, and national and regional legislative candidates.

Some voters in Jakarta clearly struggled with the process.

"The ballots with the photos on it were actually confusing. And the other one had a lot of names I didn’t recognise," said first-time voter Orlando Yudistira, 19.

In the easternmost province of Papua, voting in some areas was delayed until later this week after as many as 64 districts had not received "needed election logistics", officials said.

Flash floods destroyed three polling stations, disrupting voting, on Sumatra island, media said.

Widodo win priced in

Widodo campaigned on his record of deregulation and improving infrastructure, calling his first term as step to tackling inequality and poverty in Southeast Asia's biggest economy.

Bread and butter issues were at the forefront of the minds of many voters.

"I hope in future prices of staple foods will be cheaper, especially as we are heading into Ramadan and Eid Al Fitr," said Nurani, a 41-year-old mother of three, voting in Bandar Lampung in Sumatra.

President Joko Widodo and first lady Iriana Joko Widodo show their ink-stained fingers after casting their ballots in Jakarta. Edgar Su/Reuters

But religion has also been a factor in the election in the world's most populous Muslim-majority country where conservatives have been increasingly influential.

Widodo, a moderate Muslim from Java island, had to burnish his Islamic credentials after smear campaigns and hoax stories accused him of being anti-Islam, a communist or too close to China, all politically damaging in Indonesia. He picked Islamic cleric Amin, 76, as his running mate.

Prabowo, a former special forces commander who has links to some hardline Islamist groups, and his running mate, business entrepreneur Sandiaga Uno, pledged to boost the economy by slashing taxes and cutting food prices.

An unexpected win for the challenger could trigger a brief sell-off in financial markets that have priced in a Widodo victory, analysts say.

Reuters