Former Philippine President Rodrigo Duterte was almost certain to be elected mayor of his home city by a landslide on Monday, unimpeded by his detention at the International Criminal Court on charges of murder as a crime against humanity.

The former president's win was expected, but other races in the midterms proved less predictable.

In the southern Philippine city of Davao, a spirited mayoral election campaign is in full swing, with candidates and their supporters out canvassing for votes.