Mr Pranowo and Mr Jokowi are members of the Indonesian Democratic Party of Struggle (PDI-P).
PDI-P last month announced that Mr Pranowo would be its presidential candidate for the upcoming election.
Meanwhile, Mr Subianto declared last year his intention to run in the 2024 election.
The head of the Gerindra Party has run for president twice but lost to Mr Jokowi both times.
According to various polls, Mr Pranowo, Mr Subianto and former Jakarta governor Anies Baswedan – who has also declared his intention to run – are the favourite potential presidential candidates.
Many polls have put Mr Pranowo ahead of Mr Subianto, with Mr Baswedan coming in at the third place, but a recent survey has now put the defence minister at the top.
A survey done between April 29 and May 10 by Litbang Kompas, the research arm of national newspaper Kompas, showed that Mr Subianto had the highest electability with 24.5 per cent, which is up six per cent from the previous poll in January.
In the survey published this week, Mr Pranowo came in second place with 22.8 per cent. This is down from the 25 per cent he scored previously.
Mr Baswedan’s electability is 13.6 per cent, according to Litbang Kompas.
The latest survey results make the pairing of Mr Pranowo and Mr Subianto even more difficult, said Mr Setiadi.
“But the latest survey by Litbang Kompas shows the difference between them is very thin. The survey shows Mr Subianto is slightly ahead of Mr Pranowo, but in previous ones, Mr Pranowo was leading,” he said.
On Thursday, Mr Subianto met with Mr Jokowi at the presidential palace in Bogor, West Java, where the president resides.
There has been no official press statement on the meeting, but Gerindra’s senior official Sufmi Dasco Ahmad said that such meetings are “common”.
“Meetings between Mr Prabowo and Jokowi are common. Meetings between the president and the presidential aide as his minister, of course, are common because they must report on the programmes that have been implemented,” said Mr Sufmi Dasco Ahmad.
When Indonesian ministers meet the president, the minister secretary of state tends to have further information on the meetings.
However, Minister Secretary of State Pratikno said he did not know about the meeting as he did not accompany the president.
“I believe it is usual if the president summons his minister,” he told reporters on Thursday in Jakarta.
Indonesia will head to the polls on February 14, 2024.
Potential presidential and vice-presidential candidates would need to register with the election commission in October.