Philippines "First Daughter" Sara Duterte on Saturday entered the vice presidential race for the 2022 elections, in a surprise move that could boost the chances of presidential hopeful Ferdinand Marcos Jr winning the country's highest office.
Outgoing President Rodrigo Duterte, who is constitutionally barred from seeking a second term, also flagged plans to contest the vice presidency -- triggering chaotic scenes at the Commission on Elections office handling last-minute changes to candidacies ahead of a November 15 cutoff.
The elder Duterte "will file his certificate of candidacy for the vice presidency on Monday, that's what he said," presidential communications chief Martin Andanar told local broadcaster ABS-CBN.
But he added: "I would like to believe that that is the plan for now. We don't know if this will be the same plan by tomorrow or by Monday."
Sara Duterte, 43, had been widely expected to seek the presidency in a bid to succeed her father, and potentially protect him from criminal charges in the Philippines and International Criminal Court investigators probing his deadly drug war.
Her tilt for the country's second-highest office was immediately endorsed by the party of Marcos Jr, the son and namesake of the former dictator, to be his running mate in the poll.
"This is to confirm that Mayor Inday Sara Duterte through her representative, has filed her Certificate of Candidacy for Vice President under Lakas-CMD (party)," her spokeswoman Christina Garcia Frasco said on Facebook, confirming the Commission on Elections' announcement.
For months, Sara had insisted she wanted to serve another term as Davao City mayor in the family's southern bailiwick -- the position her father held before he was elected president in 2016 -- despite leading in surveys of voter preferences for the next president.
Speculation about her plans intensified this week after she suddenly withdrew from the mayoral contest. She also quit her regional party and joined Lakas-Christian Muslim Democrats, the national political party of her close ally and former president Gloria Arroyo.
Sara's decision to run for vice president leaves Marcos Jr in a strong position in the presidential race.
Popularly known as Bongbong, Marcos Jr has been a front runner in voter polls, ahead of celebrity mayor Francisco Domagoso, boxing great Manny Pacquiao and incumbent Vice President Leni Robredo.
In the Philippines, the president and vice president are elected separately.
There was speculation Sara had sought to persuade Marcos Jr to slide back into the vice presidential race, as the two clans sought to form a formidable alliance.
The Marcos family stronghold stretches across the country's north and centre, while the Dutertes enjoy widespread support in the south.
But Marcos Jr, who was seen walking arm-in-arm with Sara at a wedding south of Manila on Thursday, told reporters, "I will continue with my plan. I entered this race to run for president".
Political analyst Richard Heydarian told AFP: "Duterte running for the vice presidency... more or less seals Bongbong Marcos' position as the top contender, the candidate to beat in these elections."
The elder Duterte had previously said he would contest the vice presidency, before changing his mind and announcing plans to retire from politics.
But on Saturday, Duterte accompanied his close aide Senator Christopher Go to the Commission of Elections office. Go officially entered the presidential contest, after previously registering for the vice presidential race.
Heydarian said approval ratings for Sara and her father had slipped in recent months, with the momentum shifting "in favour of Marcos".
If she were to win the election, it would keep "a Duterte near the top and well positioned for a 2028 run," said Mark Thompson, political science professor and director of the Southeast Asia Research Centre at City University of Hong Kong.
Sara's decision sparked a mixed reaction from her fans, with some praising the move, while others expressed disappointment she would not seek the presidency.
"Maam please run for president, please do not abandon the legacy of your father," a supporter posted on Facebook.
Marcos Jr's presidential bid, meanwhile, already faces challenges.
Opponents have asked the Commission on Elections to disqualify him from the race over previous convictions for failing to file tax returns several decades ago.
If Marcos Jr were to win office, it would cap a remarkable political comeback since a popular uprising in 1986 toppled his father and chased the family into exile in the United States.