Jakarta governor Joko 'Jokowi' Widodo appears to be on track to become Indonesia's seventh president, after more than 180 million voters cast their ballots in the country's presidential election.

But his rival, former general Prabowo Subianto, is refusing to accept defeat in early counting, despite a clear trend in sample results indicating Mr Widodo is in the lead.

Sample counts of up to one million votes by eight reputable polling companies show the same trend: Mr Widodo with about 52 per cent of the vote, and Mr Subianto with around 48 per cent.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 2 minutes 15 seconds 2 m 15 s Jokowi edges ahead ( Greg Jennett )

These are samples, not the full official count, which is still a month away from being declared.

Mr Subianto has told supporters they need to "monitor the real count and guard this victory" - asserting that he can still win.

Mr Widodo also addressed supporters and gave examples of the quick count results which show him in the lead, but stopped short of formally declaring his own victory.

He appeared relaxed and confident as he paid his respects to his rival, saying Mr Subianto should be revered as a national figure and as a patriot.

Mr Widodo earlier appeared on national television with his party chairwoman Megawati Sukarnoputri to thank supporters.

He called for the electoral process to be allowed to "go fairly without any intervention and dishonesty".

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 44 seconds 3 m 44 s Indonesia correspondent, George Roberts ( Tony Jones )

The quick count sample method used in the exit polls has proven reliable in the past, although the official declaration by the electoral commission is still a month away.

Wednesday's elections were a massive undertaking, with 185 million voters lodging their votes across 6,000 inhabited islands.

A national public holiday was declared to allow people to vote in 470,000 polling booths across the nation.

Before election day, polls showed Mr Subianto, a former Suharto-era general who is accused of human rights violations, almost closing the gap on Mr Widodo.

Australia's relationship with new leader to be trickier

The election comes at a time when Australia is yet to fully resolve tensions with Indonesia over spying and asylum seeker boat turn-backs.

Experts warn Indonesia's relationship with Australia is likely to be more difficult, as both candidates are more nationalist than outgoing president Susilo Bambang Yudhoyono.

Professor Aleksius Jemadu, dean of political sciences at Pelita Harapan University in Jakarta, says voters weighed up two distinctly different styles.

"Look at how Jokowi, Joko Widodo, make his campaign - he presents himself as a humble leader, more people oriented," Professor Jemadu said.

But there is also a sense that Indonesians want a firmer hand after a decade of Mr Yudhoyono in power.

How does 'quick count' work? The 'quick count' is a projection of the final vote based on a sample about 2,000 polling stations

The 'quick count' is a projection of the final vote based on a sample about 2,000 polling stations An average of 300 votes are counted at each

An average of 300 votes are counted at each It has historically been an accurate gauge of the final result in Indonesian elections

It has historically been an accurate gauge of the final result in Indonesian elections Some polling firms in Indonesia are not considered credible as they are tied to particular candidates and parties.

Some polling firms in Indonesia are not considered credible as they are tied to particular candidates and parties. The Lowy Institute considers the Centre for Strategic and International Studies (CSIS), Saiful Mujani Research and Consulting (SMRC) and Indikator to be reliable polling firms.

The Lowy Institute considers the Centre for Strategic and International Studies (CSIS), Saiful Mujani Research and Consulting (SMRC) and Indikator to be reliable polling firms. The official results will be announced by Election Commission on July 22. Source: Lowy Institute/Reuters

"The Prabowo campaign, the emphasis is on high-profile, the leader of a strong nation. There's a lot to be proud of Indonesia and that's why he emphasises more on the nationalistic overtones of his campaign of his foreign policy as well," Professor Jemadu said.

Associate Professor Greg Fealy from the Australian National University says that whoever wins, Australia's relationship with Indonesia is set to become trickier.

"I think it's going to require the Australian Government to rethink its approach to Indonesia and it's going to have to factor in the likelihood that a future Indonesian government is far less likely to forgive Australia," Professor Fealy said.

"Neither of the two candidates in the current presidential election in Indonesia are as statesman-like and both of them have a far more overtly nationalist agenda and so that is likely to spell trouble if Australia is perceived as acting unilaterally or being heedless of Indonesia's desires.

"[Joko Widodo] is a more stable person in his personality and he's more pragmatic and I think more measured in his approach to difficult policy issues ... Prabowo Subianto is a much more difficult person to predict because his range of behaviour is far wider and he's extremely temperamental."