"The Jokowi camp is clearly worried that there will be fraud in the aggregation process," said Jakarta-based political analyst Paul Rowland. "There are plenty of opportunities there to change the numbers."
Confidence in the Constitutional Court has also recently been shaken, though some are already predicting that's where Indonesia's next president will be decided. Last month, its former chief justice was jailed for life for accepting bribes while ruling on a regional election dispute.
"Considering victory claims from both candidates, it seems difficult to avoid a legal battle at the Constitutional Court," said Denny Indrayana, deputy minister of Law and Human Rights. "The credibility of the Constitutional Court as the last decider of the presidential election's results is at stake."
But if it does go that far, others say they believe Subianto, 62, would accept the final ruling.
"I think Prabowo's main intention, main campaign platform was for the security, safety and stability of the nation," said Tobias Basuki, an analyst from the Center for Strategic and International Studies, which conducted one of the highly respected quick count surveys that determined Widodo as the winner. "I believe he will concede defeat, and the largest extent would be going to the Constitutional Court."
The election has energized the country of 240 million. Turnout was estimated around 75 percent in a race that was polarized by two very different figures.
Widodo, 53, of the Indonesian Democratic Party of Struggle, is the first candidate in a direct presidential election with no ties to former late dictator Suharto, who ruled for 30 years before being overthrown in 1998. Widodo is a former furniture exporter from humble beginnings who has built a reputation of being an efficient leader, getting elected to run the capital in 2012. He is seen as a man of the people and ran a more grassroots campaign.
Subianto, of the Great Indonesia Movement Party, comes from a wealthy, well-known family and is accused of widespread human rights abuses, including ordering pro-democracy activists kidnapped before Suharto's fall. He surged forward in the polls just weeks before the election after picking up endorsements from most of the country's major political parties and running a more well-oiled campaign. He appealed to many voters by vowing strong leadership that many believe has been absent with Yudhoyono, who was constitutionally barred from running after serving two five-year terms.
Associated Press writers Niniek Karmini and Ali Kotarumalos in Jakarta and Chris Brummitt in Hanoi, Vietnam, contributed to this report.