Click photo to enlarge
Former President Gloria Macapagal Arroyo emerges from a van to attend her... ((AP Photo/Pat Roque))
MANILA, Philippines—Former Philippine President Gloria Macapagal Arroyo pleaded not guilty to an electoral fraud charge Thursday at the opening of a landmark trial that is seen as a key test of her reformist successor's campaign to stamp out corruption.

Arroyo, president from 2001 to 2010, is accused of rigging the results of senatorial polls in 2007 to favor her candidates. The electoral sabotage charge is the first of several criminal cases being prepared against her.

"Not guilty," she told the court in a soft voice and with a stoic expression after her defense team waived a full reading of charge details. If convicted, she could face life in prison.

The stakes are high for both Arroyo and President Benigno Aquino III. Aquino risks losing public support if she is acquitted and his rallying cry of "no corruption, no poverty" may fizzle out as just another failed attempt to fix the graft and poor governance that have hounded the nation for decades.

Arroyo's acquittal would vindicate a former leader who has portrayed her prosecution as a political vendetta to destroy her reputation and mask Aquino's failure to improve the lives of Filipinos, a third of whom lives on $1 a day.

"Despite the continuous and massive vilification campaign against me and my family, I have always said that I will dispute all charges in the proper forum," Arroyo said in a statement, adding she wants to clear her name.