The son of former Indonesian president Susilo Bambang Yudhoyono has bowed out of the race to be Jakarta governor, paving the way for a straight fight for the post in April.

Mr Agus Harimurti Yudhoyono and running mate Sylviana Murni conceded the election late on Wednesday night after all quick counts of the polls earlier in the day showed that they had garnered less than 20 per cent of the votes.

This was less than half the votes won by Mr Agus' two rivals, the incumbent Basuki Tjahaja Purnama and former education minister Anies Baswedan, who split the remaining 80 per cent or so of the votes.

Basuki holds a slight edge.

In an impassioned speech at his campaign headquarters in central Jakarta, Mr Agus said there are winners and losers in every contest.

"But I accept defeat with dignity and with an open heart," he said to the hundreds of supporters who had gathered there hours after pollsters announced final exit poll results.

Mr Agus told the crowd that he had called to congratulate Governor Basuki. The governor and his running mate, Mr Djarot Saiful Hidayat, had managed to reclaim the lead in the polls, which they lost to Mr Agus last December after Basuki was charged with blasphemy.

"I also tried to reach Anies and Sandiaga but, unfortunately, they were still busy," Mr Agus said, referring to Mr Anies and businessman Sandiaga Uno from the Gerindra Party. "And God willing, what I have done will benefit me in my later life," he added, triggering shouts of "Agus for president".

Some pundits felt the public outburst by his father, who accused the government of wiretapping his phone and organising a "black campaign" to hinder Mr Agus' campaign near polling day, did the candidate more harm than good.

Indikator Politik Indonesia executive director Burhanuddin Muhtadi said Mr Agus was doing well in the snap polls until his father's tirade on Twitter.

"I think Yudhoyono's involvement in the Jakarta election backfired," said Mr Burhanuddin in The Jakarta Post yesterday.

The official result of the closely watched election will be out only on March 4 but is expected to mirror the exit polls, analysts say.

As none of the candidates appears to have polled at least 50 per cent of the votes, as is required for a win, a second round of voting will be held on April 19, with the Basuki-Djarot pair facing off against the Anies-Sandiaga team.

The candidates will campaign from April 6 to 15, before a three-day cooling-off period. The results are expected only in May.