JAKARTA (Bloomberg) - Indonesian President Joko Widodo's lone challenger in next year's election, Prabowo Subianto, has a long way to go to catch up with the incumbent's social media popularity as the candidates seek to seize early campaign momentum.

Widodo, known as Jokowi, has 10.2 million followers on his personal Twitter account compared with 3.17 million for Subianto.

The incumbent president also outnumbers his only challenger on Instagram eight-to-one, while Subianto has about one million more followers than Jokowi on Facebook.

Jokowi, also a regular vlogger, has more than 570,000 followers on his Youtube channel, while a search showed no dedicated channel for Subianto.

Social media is set to be a key battleground for the candidates fighting the April election in a country that boasts of more than 100 million smartphone users who are active on Facebook, Instagram and Twitter.

With an estimated 70 million first-time voters to woo, the candidates are embracing technology like never before.

Jokowi, 57, is bidding for a second five-year term and has picked the country's top Muslim cleric as his running mate in an attempt to find favour with both liberal and conservative voters.

"The number of millennials could be about 40 to 50 per cent of total voters," said Usep Ahyar, a director at Populi Center, a Jakarta-based pollster.

"Candidates who can secure the millennials have a bigger chance to win the election."

Jokowi, who's fond of sporting T-shirts, jeans and sneakers and often displays his love for super bikes, may hit it off with millennials than 66-year-old Subianto, a former general who's often seen in his khaki trousers and white shirts and loves riding horses.

But when it comes to the running mates, Sandiaga Uno, Subianto's vice presidential pick is more social media savvy than Ma'ruf Amin, Jokowi's 75-year-old running mate.

Uno, a former private equity executive and deputy governor of Jakarta, has about 1.5 million followers on Instagram and close to a million followers each on Twitter and Facebook. Amin has about 105,000 followers on Instagram and the last post on Facebook was in February 2016 while he had no verified Twitter account.

"When filing his nominations, Jokowi was playing with the symbols. He came wearing a trendy shirt with a caption - Clean, Humble, Concrete Action," Ahyar said.

"Jokowi is ahead in everything."

Official campaigning for the presidential election will begin in September with voting scheduled for April 17.