MANILA (AFP) -- Filipinos headed to the polls on Monday in a vote that is expected to strengthen President Rodrigo Duterte's grip on power, opening the way for him to deliver on pledges to restore the death penalty and rewrite the constitution.
More than 18,000 positions are at stake, including half of the seats in the upper house Senate, which has served as a bulwark against some of Duterte's most controversial policies.
Duterte is known internationally for his foul-mouthed tirades and deadly drug war, but remains hugely popular among Filipinos fed up with the country's general dysfunction and leaders who have failed to fix it.
He wants to bring back capital punishment for drug-related crimes as part of his narcotics crackdown, in which thousands of alleged pushers and users have already been killed by police.
His tough-on-crime platform -- which also includes lowering the age of criminal responsibility from 15 to 12 -- was key to his landslide election victory in 2016.
Crowds gathered at voting centers in the capital Manila even ahead of polls opening at 6:00 am (2200 GMT Sunday) in an election where some 61 million are registered to cast ballots.
The opening of the polls saw isolated outbursts of violence, which is not unusual in the Philippines' frequently bloody competition for elected posts.
At least 20 people were killed and 24 wounded in election-related violence in the run up to the vote, according to an official count.
The military said nine people were shot and wounded Monday during a confrontation at a polling station on the restive southern island of Jolo, which is home to insurgents and powerful local clans.
Several other small clashes were reported in the south, including one in which two men were wounded by gunfire in Maguindanao.
The violence is more frequent in lower level races and will not likely be a major feature in the election's main contest for the Senate.
Winning a Senate majority, something that independent national surveys indicate is well within reach, would give Duterte legislative backing for his anti-crime proposals and his plan to rewrite the constitution.
It would also allow him to expand his anti-drug crackdown by bringing back the death penalty, a pledge that the UN Human Rights Council said caused it "deep alarm".
The Philippines outlawed capital punishment in 1987, reinstated it six years later and then abolished it again in 2006.