As the race for the presidency tightens, mudslinging between supporters of Jakarta Governor Joko "Jokowi" Widodo and ex-general Prabowo Subianto is increasing, forcing even the police to get involved.
Jokowi's team asked the police this month to arrest the publisher of a little-known tabloid after it falsely reported that the Muslim governor from the Javanese city of Solo was an ethnic Chinese Christian.
A national police spokesman said authorities were investigating the case against Obor Rakyat, or People's Torch, a newspaper available in Islamic boarding schools and mosques across Java.
Jokowi has been forced to defend himself against the attacks, which are mainly focused on his race and religion - potent topics in a country that is 95 percent native Indonesian and has the world's largest Muslim population.
Some opinion polls show that Jokowi's once huge lead over Prabowo has shrunk to single digits, a rapid decline that pollsters attribute to a successful smear campaign against the frontrunner ahead of the July 9 election.
"People in rural areas and people with middle to lower income and education tend to believe the black campaign (against Jokowi). That is why the electability of Jokowi is decreasing significantly," said Burhanuddin Muhtadi, the executive director of pollster Indonesian Political Indicator, which surveyed thousands of potential voters on the topic.
Jokowi's party, the Indonesian Democratic Party of Struggle, recently posted a photo on social media showing the candidate among Haj pilgrims in 2003, proof, it said, that he is Muslim.
Meanwhile, some of Jokowi's supporters have stepped up their own negative campaigning against Prabowo.
Wimar Witoelar, a Jokowi supporter and former spokesman of former president Abdurrahman Wahid, apologised last week for posting on his Twitter and Facebook accounts a picture of Prabowo's team alongside Osama bin Laden and other militants, according to the Jakarta Post.
Attacks against Prabowo have also included questions about his mental well-being and claims that he is a Jordanian citizen.
But the majority of the negative campaigning has been on Prabowo's human rights record as a top general, in particular during unrest that brought down his former father-in-law and long-serving autocrat Suharto in 1998.
Wiranto, Prabowo's former military boss and now a leader of a small party backing Jokowi, has released details of a military council's findings which said Prabowo had deliberately misinterpreted orders and told troops who were not under his command to arrest political activists.
Wiranto insisted that he was not making the announcement in his capacity as a politician.
Face to face, the two candidates have been the epitome of civility. At two presidential debates, they have hugged and shaken hands and left it to their vice presidential running mates to attack the other.
Muhtadi, from the polling agency, said the attacks on Prabowo's human rights record were not as effective as the smear campaign against Jokowi because the former general's past was already largely known.
"Prabowo's human rights issues are not really influencing voter behaviour when compared to the black campaign against Jokowi," Muhtadi said.
"This is why it is hard to predict who will be the winner in the next election."