The Philippine president Rodrigo Duterte’s daughter has registered her candidacy for vice-president in next year’s elections and was chosen as the running mate of Ferdinand Marcos Jr, the son of the late Filipino dictator, in an alliance that has alarmed human rights activists. Sara Duterte backed out this week from her reelection bid as mayor of Davao City in the south, then took the place of a largely unknown vice-presidential candidate of her political party, Lakas CMD, in a move that allowed her to seek the second-highest post even after a deadline lapsed for candidates in the 9 May elections. Marcos Jr filed his papers at the Commission on Elections last month. His federalist party, PFP, on Saturday named Sara Duterte as his running mate. Philippine presidents and vice-presidents are elected separately and could forge an alliance even if they run under different political parties. If elected from rival camps, they often end up in a hostile relationship. Ferdinand Marcos, who was toppled in a 1986 pro-democracy uprising and died in US exile three years later, and the current president have both been criticised for gross human rights abuses. Marcos placed the Philippines under martial law in 1972 in an era that was marked by widespread atrocities and economic plunder. Duterte has been condemned by western governments and human rights groups for a brutal anti-drugs crackdown that has left more than 6,000 mostly poor suspects dead in large-scale killings that are being investigated by the international criminal court. “The Marcos-Duterte tandem is the biggest threat to the democratic aspirations of the people,” said Renato Reyes of Bayan, a prominent leftwing coalition. “It has the most self-serving aims: a Marcos restoration and the protection of outgoing president Rodrigo Duterte.” The Duterte-Marcos alliance “serves only the narrow interests of their dynastic families”, added Reyes. His group immediately launched an online protest and scheduled a rally at the country’s commission on human rights for Sunday. There were no immediate comments from Sara Duterte or Marcos Jr, a former senator and provincial governor who is widely known by his nickname Bongbong. Initially, Duterte and his ruling party wanted his daughter to succeed him. That prospect has renewed calls for the Philippine congress to enact a law to ban political dynasties in a south-east Asian country where powerful and wealthy clans have dominated local politics for generations. Sara Duterte, a 43-year-old mother of three and a lawyer like her father, has been a longtime mayor of Davao. The economically vibrant city is where the elder Duterte first carved a political name with his populist rhetoric and often bloody approach against criminality, especially the widespread trafficking and use of illegal drugs, before he rose to the presidency in 2016. Duterte’s rule, which ends in June next year, became one of the most tumultuous and controversial in Philippine history, after Marcos. The ailing president, known for his brash rhetoric and expletive-laden outbursts against domestic critics, western leaders and even the pope, initially planned to run for vice-president. But he backed out after his popularity ratings dropped, prompting him to announce his retirement – although he has walked back on such public declarations in the past. The president has said he is ready to face a possible array of criminal complaints for his deadly campaign against illegal drugs when he steps down but would never cooperate with the international criminal court’s investigation. Marcos Sr died in exile in Hawaii in 1989 without admitting any wrongdoing, including accusations that he and his family amassed an estimated $5bn to $10bn while he was in power. Marcos Jr has called the allegations against his father “lies”. At least six groups of petitioners have asked the elections commission to either cancel or reject his candidacy, citing a 1995 tax evasion conviction. He has played down the petition as the work of political opponents. At least five key candidates have declared their intention to succeed Duterte, including the vice-president, Leni Robredo, the opposition leader who narrowly defeated Marcos Jr in the 2016 vice-presidential race. She has criticised him for his refusal to apologise and express remorse for his father’s dictatorship.