Jakarta, Indonesia - In a spacious room in a downtown office building, a few dozen young people are glued to their computer screens, raptly Facebooking and tweeting.

But they're not procrastinating from work, as it might appear - they're electioneering. As Indonesia gears up for presidential elections on July 9, Facebook, Twitter, blogs and online forums are abuzz over one of the country's most polarising races since its transition to democracy in 1998.

Indonesia has been called the "social media capital of the world" and residents of Jakarta, the capital, have been found to tweet more than any other city on Earth. That's despite the fact that internet penetration is low throughout much of the country.

"Now the real battle is on digital media. People don't want to see banners and T-shirts and stickers everywhere," said Noudhy Valdryno, the 21-year-old leading the Gerindra party's social media campaign. Battling it out online is also "way, way cheaper", he added.

When [Jokowi] ran for the governor of Jakarta, the social media was buzzed with him: 'You are somebody new, you are somebody different from the regular bureaucrats, the corrupt officials.' - Yohanes Sulaiman, political analyst

Gerindra's candidate is former special forces commander Prabowo Subianto - who, Valdryno said, used social media sites as early as 2000. The party has hired about 75 people to promote the candidate online.

Prabowo's opponent in the race, Jakarta governor Joko "Jokowi" Widodo, is also a strong online contender: His supporters' creative use of social media was credited for his victory in the 2012 governor's race, in which he unexpectedly toppled the incumbent.

The number of internet users in Indonesia has more than doubled since 2009, when the last presidential polls were held. The young tend to be the heaviest users - and since half of Indonesia's population is under the age of 28, candidates are hoping that online campaigns could yield ballot-box bonuses.

'You are somebody new'

But do retweets, likes and pageviews translate into support on election day?

Conversations that start online radiate beyond the mostly urban, affluent users of social media - who are "social influencers in their environment, online and offline", said Yose Rizal, the co-founder of PoliticaWave, an Indonesian social media monitoring group that is consulting for Jokowi's campaign.

Social media activism has already had off-line effects on the country's politics.

In 2012, Indonesia's Corruption Eradication Commission (KPK) began investigating a corruption case involving high-level police officials. But the national police refused to cooperate with the investigation. Enraged Twitter users created the hashtag #SaveKPK, urging President Susilo Bambang Yudhoyono to intervene and side with the anti-corruption watchdog - which he did, claiming his decision was influenced by the brouhaha on social media.

That same year, Jokowi - the mayor of a city in Central Java who came from a humble background - was the surprise winner of Jakarta's governor's race, portraying himself as a fresh face who would clean up corruption and run the megalopolis more efficiently.

"One of the reasons Jokowi could become a national figure like [he is] today is because of social media," said political analyst Yohanes Sulaiman. "When he ran for the governor of Jakarta, the social media was buzzed with him: 'You are somebody new, you are somebody different from the regular bureaucrats, the corrupt officials.'"

Jokowi supporters created a popular adaptation of the mobile game "Angry Birds", in which the politician throws exploding tomatoes at corrupt officials. And a music video remaking the boy band One Direction's song What Makes You Beautiful - in which Jakartans complained about the city's traffic, corruption and flooding problems, expressing hope that Jokowi would fix them - went viral, garnering more than two million views.

Top-down versus bottom-up

But creativity only goes so far. Merlyna Lim, a digital media expert at Canada's Carleton University, said while Jokowi's online supporters are funny and innovative, Jokowi's opponent has outmanoeuvred him online.

"Prabowo has been better in mobilising [online]," she said. "They're more systematic … they have more organised attempts to attack [Jokowi]."

Social media creates a space where you can consume information that is not 100 percent true. Major news organisations here can report on [rumours circulating on social media] without having to verify the original source. - Enda Nasution, blogger

Prabowo's centralised, top-down social media campaign markets the candidate as a strong, decisive leader. That messaging has swayed voters like Fitri, a 20-year-old working at a pop-up Hello Kitty store in a Jakarta mall. She said she supports Prabowo partly because, judging by his Facebook page, he promises stability and "looks like Suharto", the authoritarian leader who ruled Indonesia for more than three decades.

And Valdryno said his team aims to respond to questions asked on social media networks about Prabowo within 15 minutes.

By contrast, Jokowi's online efforts rely on volunteers affiliated with around two dozen social media "tribes". Some tribes work on attacking Prabowo, others are tasked with defending Jokowi, or focus on whipping up creative memes.

"On a daily basis we communicate by WhatsApp groups - one for each tribe," said Romanus Sumaryo, who heads Jokowi's social media campaign.

The approach has its advantages: Building on existing networks of online supporters, Sumaryo said the campaign "didn't have to create or engineer the social media environment", but could count on legions of Jokowi partisans to rally online.

But the decentralised approach has also meant that the Jokowi campaign has been slow to respond to online smears against him.

The 'black campaign'

Although online memes supporting the candidates are often playful, social media has also been used for more nefarious purposes.

In the past few months, Jokowi has been hit with allegations, spread online as well as in some tabloid newspapers, that the candidate - who is Muslim and ethnically Javanese - is secretly a Christian or ethnically Chinese. Others have claimed that his parents are Singaporean.

Such tactics, collectively known in Indonesia as the "black campaign", may be having an effect. Jokowi - who for months had polled ahead of his opponent by double-digit margins in public opinion surveys - has plummeted in the polls, putting Prabowo within striking distance.

Prabowo's campaigners deny any connection with the smears. "It is an attack from the people, a very sporadic phenomenon," said Valdryno. "That is why we always emphasised the importance of using an official account, so we can be responsible for anything that we post online."

Meanwhile, on the other side, rumours have also circulated online that Prabowo is a citizen of Jordan. He lived in the country for three years, but denies accepting citizenship.

Attacks against Prabowo are mostly "talking about human rights abuses, him getting fired from the military. [The abuses are] something that you cannot really prove," said Sulaiman. Prabowo has admitted involvement in the abduction of several activists in 1998 - some of whom were tortured during their detention - though he denies responsibility for their torture, and has never been criminally charged with wrongdoing.

"But in Jokowi's case, it's like he's a closet Christian, his father is a Chinese … this Manchurian candidate. You get the point," said Sulaiman. "It's crazy."

Fanning the flames

Smear tactics are nothing new to Indonesia's rough-and-tumble politics. But technology has, analysts say, made it easier to inflame and keep alive unsubstantiated rumours or outright lies.

In the past, political discussions online responded to the debate within Indonesia's newspapers and TV stations. But in this campaign, it's often the other way around.

"Social media creates a space where you can consume information that is not 100 percent true," said Enda Nasution, who has been often been referred to as the "father of Indonesian bloggers".

He explained that major news organisations in Indonesia could report on rumours circulating on social media without having to verify the original source.

"For example, Jokowi could be a Muslim … and mainstream media has been reporting that on social media there's a lot of controversy about [that], without having to verify whether that fact is true," he said.

Techno-pessimists have long doubted the internet's potential to make positive contributions to political debate. Nuanced discussions are rare on social media - it's hard to go into much depth within Twitter's 140-character posts - and attention spans tend to be short.

But Lim said Jokowi was able to win the Jakarta governor's race in 2012 by portraying himself online as "cool, honest, clean, down to earth … everything that Indonesian politicians were not. His policies were sound, but for the voters these were secondary to Jokowi himself".

And perhaps it's this premium that social media places on character, using simple, visceral messaging, that's breaking against Jokowi this time around. People are not able to "digest something complex like human rights violations" - such as those alleged against Prabowo, Lim said. "But rumours like Jokowi not being Muslim are going viral."

Follow Sam Bollier on Twitter: @SamBollier