MANILA, Oct 1 (Reuters) - The Philippines opens a week-long window on Friday for filing of candidacy for thousands of political posts, from the presidency down to town councillors, kicking off what is expected to be a hotly contested election in May next year. The process should put an end to months of speculation over who will vie to succeed firebrand President Rodrigo Duterte, 76, who under the constitution cannot seek reelection and will contest the vice presidency race instead. read more What is usually a festive event with big crowds will be more sober this year, with restrictions in place to fight one of Asia"s deadliest COVID-19 epidemics. So far, just three contenders have declared their intention to run for president, the most famous, senator and newly retired boxing icon, Manny Pacquiao. Manila Mayor Francisco "Isko Moreno" Domagoso, a former actor, and Senator Panfilo Lacson, an ex police chief, have also confirmed they will run. But the spotlight will be on Sara Duterte-Carpio, the president"s daughter, despite her ruling out running for higher office next year. Duterte-Carpio, 43, replaced her father as Davao City mayor when he became president, and she remains by far the most popular presidential prospect, according to successive opinion polls this year. Analysts say it is crucial her father"s successor is a loyalist, to insulate him from potential legal action at home or by the International Criminal Court, over the thousands of state killings in his war on drugs since 2016. Critics say his interest in the vice presidency is also a self-preservation move. Duterte says his motivation is public service, not power. Vice president, Leni Robredo, who leads the opposition, is also being urged by supporters to run for the top post. "In the coming days, please pray with me so that our decision will be what is best for our country," she said. More than 60 million Filipinos will vote in May 2022 for a new president, vice president, and more than 18,000 lawmakers and local government officials. Candidates have until Oct. 8 to register, but withdrawals and substitutions are allowed until Nov. 15, leaving scope for last-minute changes of heart, like the 11th hour entry of Duterte for the 2016 election, which he won by a huge margin.