A massive petition campaign to change the structure of the Philippines' form of government looks to have been in vain. The bid to change the two-house system of House and Senate into a one-house parliament is an initiative of President Gloria Macapagal-Arroyo's government, which has been troubled by a restive Senate. But the attempt to trigger a referendum on the issue via the collection of 10 million signatures was dismissed yesterday, surprisingly by the pro-Arroyo Commission on Elections. 'That is a temporary setback,' said Governor Ben Evardone, spokesman for the group of pro-Arroyo governors and mayors who banded together to collect the signatures that were submitted to the commission last Friday. Mr Evardone said the campaign would continue, and the group would file a complaint with the Supreme Court today over the issue. The six commissioners, all Arroyo appointees, yesterday unanimously ruled in support of a 1997 Supreme Court decision that struck down a law enabling petitions to trigger referendums on the constitution. The commission said the invalidated law, which is still on the books, 'remains nothing but an empty right and this commission is permanently enjoined from entertaining ... any petition for such an initiative'. Mrs Arroyo's spokesman, Ignacio Bunye, said the battle to change the constitution was not over. 'What happened now is just the initial stage. What is important is the decision of the Supreme Court and the people,' he said. Opposition leader Jejomar Binay said he was suspicious of the commission's ruling. He noted that while the commission's rulings sometimes took years, this one took days. He claimed the ruling was 'a mere ploy' to lull the opposition into thinking it had won the fight. But Christian Monsod, whose group 'One Voice' has been opposing Mrs Arroyo's charter change moves, expressed optimism that the Supreme Court would stand by its 1997 ruling. 'Frankly, I don't think it will come to that. I think the Supreme Court will dismiss the petition,' he said. An alternative means of changing the constitution is for Congress to directly propose the amendments. Amendments can be made with a three-quarters majority vote, but it is unclear whether that would have to be achieved at a joint sitting of the House and Senate or at two separate sittings. Separate sittings would doom any amendments, since Mrs Arroyo lacks support in the Senate. A joint sitting would narrow the difference.