(Adds Aquino comment on discretionary fund)
By Manuel Mogato
MANILA, July 14 (Reuters) - Philippine President Benigno Aquino's performance ratings have plunged to their lowest ever, two independent pollsters said on Monday, as a perception grew that he is not serious enough in efforts to fight corruption.
Aquino, the son of an assassinated opponent of dictatorship and his wife, a democracy hero and former president, won the presidency in 2010 on a promise of good governance and fighting graft but has struggled to rid the country of its image as the most corrupt in Asia.
A survey by independent pollster Pulse Asia, taken last month, showed Aquino's approval rating dropped from 70 percent in March to 56 percent. His trust rating also fell from 69 percent to 53 percent in the same period.
Another survey, by Social Weather Stations, also done last month, showed Aquino's net satisfaction ratings dropped to 25 percent from 45 percent in March, the lowest in four years. His highest was 67 percent in August 2012.
Aquino is ineligible for re-election under the constitution but the prospects for his Liberal Party's candidate are likely to be damaged if his popularity is undermined in the run-up to a 2016 presidential election.
"This is the largest decline in both approval and trust and it's also his lowest performance thus far," Ana Maria Tabunda, Pulse Asia research director, said in a television interview.
People were disillusioned by widespread corruption in government, she said, adding that her poll was taken at the same time that the government arrested three senators on plunder charges for misuse of congressional funds and rising cost of rice and other food.
Tabunda said the survey was largely complete by the time the Supreme Court rejected an Aquino creation of a discretionary fund, called the Disbursement Acceleration Program (DAB), which has become the administration's worst crisis in four years.
Edwin Lacierda, the president's spokesman, acknowledged a "dip in enthusiasm" but said he was not alarmed.
"These numbers can be considered par for the course or average for this period," he said. "A healthy majority has expressed trust and confidence in the president."
Since 2010, Aquino has enjoyed high approval and trust ratings of more than 70 percent, rising to 80 percent, his highest, in early 2012.
But his approval could be further undermined as the ramifications of the scandal over the discretionary fund play out.
"The president has to make drastic measures, like displaying impartiality in the corruption cases meaning he has to crack the whip even on his own allies," said Earl Parreno of the Institute for Political and Electoral Reform, an independent research group.
"If he continues to protect allies, then it will be hard to stop the skid."
Last week, Aquino retained the budget secretary who took responsibility for creating the DAP fund and has offered to resign.
Aquino defended the DAP on Monday evening, saying in a televised speech the Supreme Court had been wrong to strike it down and the government would appeal against the decision.
"DAP is good. Our intentions, our processes, and the results were correct," he said, adding that the Supreme Court was trying to block his reforms.
"We find it difficult to understand your decision," he said, referring to the court. "We ask that you review your decision, this time taking into consideration the points I have raised tonight." (Editing by Robert Birsel)