Philippine President Rodrigo Duterte on Tuesday withdrew his bid to become a senator, the same day his preferred successor quit the presidential race.

The president filed withdrawal papers at the election commission a few hours after longtime aide, Senator Christopher “Bong Go” did the same, a decision Duterte’s spokesman said was to enable him to better serve the country.

The constitution bars Mr. Duterte from seeking reelection as president, but he was allowed to run for other positions in nationwide elections in May 2022.

He had planned to pursue the vice presidency, but chose instead to seek a seat in the powerful senate.

The withdrawal is the latest twist in a Philippine election race fraught with last-minute changes and surprises that have baffled political experts.

Mr. Go was not performing well in opinion polls and it is unclear who will have the endorsement of Mr. Duterte, who has maintained consistently high approval rating since he won the 2016 election as an outsider promising to fight crime and drugs.

The idea perhaps is continuity but how can there be continuity if there is no candidate for president for the administration? said political analyst Mr. Edmund Tayao.

The president’s daughter, Ms. Sara Duterte-Carpio, had been tipped to succeed him, but she opted instead to run for vice president alongside the son of the late dictator, Mr. Ferdinand Marcos, who has emerged as an early frontrunner.

On Tuesday, she said she supported her father’s decision.