JAKARTA: The eldest son of Indonesian President Joko Widodo is among the "strongest" potential running mates for Prabowo Subianto, a retired general who is a leading contender in next year's presidential election, a party official said on Tuesday.

The former special forces commander is running for a third time after having lost twice to Jokowi, as the president is popularly known, and there has been speculation for months that Jokowi's son, Gibran Rakabuming Raka, would run for the vice presidency with Prabowo.

The 36-year-old mayor of Surakarta city was ineligible because of his age until the Constitutional Court on Monday ruled that anyone elected to regional posts can contest the 2024 election regardless of age.

The ruling has sparked outrage in the world's third-largest democracy. Critics have slammed the integrity of a court where Jokowi's brother-in-law is chief justice.

Under Indonesia's constitution, presidents can only serve a maximum two terms, and critics accuse Jokowi of seeking to retain power after leaving office by engineering an alliance between his son and Prabowo.

"Gibran is certainly one of the strongest candidates for Prabowo's VP... especially, after the Constitutional Court approved the petition that made him eligible to run," said Andre Rosiade, an official at Prabowo's Gerindra party.

Besides Gibran, the shortlist of running mates for Prabowo includes East Java Governor Khofifah Indar Parawansa and State-owned Enterprises Minister Erick Thohir, he added.

A final decision will be made in the coming days at a meeting of all party chiefs in Prabowo's seven-party alliance, Andre said.

The same seven parties have agreed to back Gibran for Prabowo's vice president, according to a report in news portal Katadata citing an alliance party official. Reuters could not independently verify the report.

Candidates and their running mates are expected to register with the election commission between Oct 19-25.