Allies of Philippine President Ferdinand Marcos Jr looked set to win at least half of the available Senate seats in a midterm election on Monday, an unofficial tally showed, in a contest seen as a referendum on his leadership and a fierce proxy battle with his estranged vice president.

Former President Rodrigo Duterte, who faces international court charges of crimes against humanity, appears to have been elected mayor of Davao City. One of his sons is expected to fill in.

Here’s what to know about the crucial midterms and the rival dynasties at the heart of the Southeast Asian nation’s politics.