MANILA (Reuters) -- Nearly 50 percent of Filipinos distrust President Gloria Macapagal Arroyo six months ahead of congressional elections, an independent survey showed on Tuesday.

Private pollster Pulse Asia said Arroyo's distrust rating increased by 4 percentage points to 48 percent after her campaign to shift the country's political system to a parliamentary setup was defeated last month in the Supreme Court.

Critics said Arroyo, who has failed to shake suspicion she cheated in the 2004 presidential election, was promoting the political switch to stay in power after 2010, when she finishes her last term as president.

Arroyo's allies in the lower house have twice defeated impeachment bids against the former economist amid the vote-rigging allegations and her political future could be in jeopardy if they lose their majority in next May's elections.

Political analysts said Arroyo's continued failure to gain support from the country's poor would impact on the chances of her candidates to win seats in the two chamber Congress and in 17,000 local positions.

The survey of 1,200 people, conducted between Oct. 21 and Nov. 8, has a margin of error of three percentage points, Pulse Asia said.