Millions of Filipinos thronged primary schools and other polling stations on May 9 to elect a new president, with the son of former dictator Ferdinand Marcos the favourite to win the high-stakes election.

Nearly 40 years after the patriarch was deposed by a popular revolt and the family chased into exile, Ferdinand Marcos Junior looks set to complete their remarkable comeback from pariahs to the peak of political power.

Ten candidates are vying to succeed President Rodrigo Duterte in elections seen by many as a make-or-break moment for the Philippines’ fragile democracy.

But only Marcos Jr and his rival Leni Robredo, the incumbent vice president, have a credible chance of winning.

People wearing masks began forming long queues before dawn to cast their votes when polling stations opened across the archipelago.

At Mariano Marcos Memorial Elementary School in the northern city of Batac, the ancestral home of the Marcoses, voters waved hand fans to cool their faces in the tropical heat.

Bomb sniffer dogs swept the polling station before Marcos Jr arrived with his younger sister Irene and eldest son Sandro.

They were followed by the family’s flamboyant 92-year-old matriarch Imelda, who was lowered from a white van while wearing a long red top with matching trousers and slip-on flats.

Sandro, 28, who is running for elected office for the first time in a congressional district in Ilocos Norte province, admitted the family’s history was “a burden”.

But he added: “It’s one that we also try to sustain and protect and better as we serve.”

Casting her ballot for Robredo at a school in Magarao municipality, in the central province of Camarines Sur, Corazon Bagay said the former congresswoman “deserves” to win.

“She has no whiff of corruption allegations,” said the 52-year-old homemaker. “She’s not a thief. Leni is honest.”

Supporters chanting “Leni, Leni” greeted Robredo as she arrived at the same school to vote.

Turnout is expected to be high among the more than 65 million Filipinos eligible to vote.

“The long lines are magnificent. Filipinos wanted to be heard and heard loudly,” said George Garcia of the Commission on Elections.

At the end of a bitter campaign, polls showed Marcos Jr heading towards a landslide. He had a double-digit lead over Robredo in the latest surveys and she will need a low turnout of Marcos Jr voters or a late surge of support for her to score an upset.

In the Philippines, the winner only has to get more votes than anyone else.

Since Robredo announced her bid for the top job in October, volunteer groups have mushroomed across the country seeking to convince voters to back what they see as a battle for the country’s soul.

But relentless whitewashing of the elder Marcos’s brutal and corrupt regime, support of rival elite families and public disenchantment with post-Marcos governments have fuelled the scion’s popularity.

After six years of Duterte’s “authoritarian” rule, rights activists, Catholic church leaders and political analysts fear Marcos Jr will be emboldened to lead with an even heavier fist if he wins by a large margin.

“We think it will worsen the human rights crisis in the country,” said Cristina Palabay, secretary-general of human rights alliance Karapatan.

While Marcos Jr had a 75 per cent chance of winning, the outcome was not guaranteed, according to Eurasia Group analyst Peter Mumford, who said potential complacency among his supporters could work in Robredo’s favour.