Filipinos chose local and congressional representatives in elections likely to do little to ease political instability amid campaign violence that has killed at least 116 people — including three during Monday's polling.

Opinion polls showed the opposition certain to hold onto control of the Senate.

The House of Representatives was likely to remain in the hands of President Gloria Macapagal Arroyo's backers, which would doom any effort to launch a third impeachment bid against her over allegations that she fixed the 2004 election.

Security forces were on full alert in a country prone to election violence. At least 116 people have died and 121 others were wounded since campaigning began in January, police said.

In the latest bloodshed, a village chief in Bucay township in northern Abra province was fatally shot Monday in a scuffle when he questioned the presence of unidentified armed men, police said.

On southern Basilan island, gunmen opened fire on a group of voters led by a mayoral candidate inside a school voting precinct, killing one and wounding three others. In another town on Basilan, one voter was killed and another wounded, and unidentified men set fire to a school building where voting was scheduled, police and military officials said.

Also in the south, a passerby was wounded when a bomb made from a mortar shell exploded in Sultan Kudarat province, said regional police chief Joel Goltiao. In neighboring Maguindanao province, two men on a motorcycle lobbed two grenades into a school compound, wounding one, Goltiao said.

Police also warned that communist guerrillas planned to attack military and civilian targets to undermine the balloting and embarrass the government.

The race largely is seen as a proxy war between Arroyo, a daughter of the political elite, and her predecessor, Joseph Estrada.

Despite being forced out of office in January 2001 in the country's second "people power" revolt and going on trial for corruption allegations, Estrada has maintained much of his popularity among the poor for his action film career in which he frequently portrayed underdog heroes.

Arroyo's six years in power have been a mixed bag of steadying the economy while lurching from crisis to crisis, including at least two coup plots, terrorist attacks and a string of natural disasters.

"The Philippines needs change, we are No. 1 in Asia in corruption," said bus driver Efren Santos, 58. "I voted for people who can change this country because it is becoming poorer."

But while Arroyo's approval ratings are low, no major shifts are likely with general disenchantment among the poor majority offset by the stock market rising 12 percent this year and the peso hitting its strongest level against the U.S. dollar since October 2000.

Filipinos are electing 12 out of 24 senators, all 236 House of Representatives members and nearly 17,500 governors, mayors and other local officials. Vote counting is done by hand, so final results are weeks away.

Turnout of 75 percent was projected among the 45 million registered voters, elections spokesman James Jimenez said.

Several groups allied with the influential Roman Catholic Church and big businesses placed full-page newspaper advertisements on Sunday calling on Filipinos not to sell their votes amid fears of cheating.

"Remember: the candidate who wins by cheating will also govern by cheating," said Archbishop Angel Lagdameo, head of the Catholic Bishops' Conference of the Philippines.

"The citizens who sell their votes for any price deserve the government they install with their votes," he said.

Some voters in Manila complained they could not find their names on the voting register.

In southern Maguindanao, armed men snatched four ballot boxes filled with election documents that were being transported by teachers, Goltiao said.

The Commission on Elections postponed voting in Pantar township in Lanao del Norte province, after it disapproved the registration of 2,000 voters for unclear reasons. In nearby Pantao township, officials discovered 3,702 ballot forms were missing.

"I think there won't be much change. I am a little bit disheartened. I do not trust our politicians. There will always be cheating," said garment cutter Nancy Larga, 35, after voting in Manila.

For all the violence, elections also are a festive affair. Bunting hangs on the streets made out of posters of different candidates. Food vendors took positions near the entrance of polling stations.

The House races are generally regional popularity contests. So most eyes are on the Senate, where the top 12 vote-getters nationwide will win seats. Among those considered to be fighting for the final two or three slots is Gregorio "Gringo" Honasan, a military officer on bail while fighting allegations of involvement in several coup plots.