MANILA, Philippines ? (UPDATE 3) Pampanga Representative Gloria Macapagal-Arroyo began her first day as a lawmaker by attempting to resurrect Charter change.

Arroyo and her son, Camarines Sur Representative Diosdado Arroyo, co-authored House Resolution 8 which calls for a constitutional convention to propose amendments to or the revision of the 1987 Constitution.

Staff members filed the measure, which if successful, could change the system of government to one ruled by a prime minister rather than a president.

Arroyo also filed a bill to protect all species of sharks and rays in the country, and co-authored seven other bills with her son.

When sought for a reaction, Edwin Lacierda, spokesman for President Benigno Aquino III, said they were neither alarmed nor surprised by the move and downplayed this, saying Arroyo did not have the support in the House of Representatives to succeed.

?Her heart has always been to amend the Constitution. That's not a surprise to us,? Lacierda told reporters at a press briefing Thursday.

?Of course, it's something that we will be dealing with and together with our legislative partners in the House so it?s not something that we?re very bothered with. It's something that we expect already from the very start,? he said.

"The filing of the Charter change [resolution] is not a threat as far as we are concerned," he said.

"If we are able to convince the members of the House that this is not a valid or a good time to amend the Constitution, then that will be dead in the water."

But Lacierda said they were not ruling out the possibility that Aquino could intervene and mobilize his allies in the House to block the passage of the measure.

?It's possible. I don't know yet,? Lacierda said, pointing out that the President might not be aware of it yet as he was meeting foreign dignitaries when the news of Arroyo?s filing came out.

In any case, Malacañang was leaving it up to Congress to act on Arroyo's bill, he said.

?Well if she filed the bill, let's see. Let the legislative process take it course. Let's see. Do we have any say on that? Let the legislative department handle that,? he said.

Asked what he thought were the chances of the bill to get the nod of Congress, Lacierda said, ?It's too early to tell.?

Arroyo, who was required by constitutional term limits to stand down after nearly a decade in power, has long been suspected of wanting to continue leading the country.

She took the unprecedented step for a sitting president of contesting, and winning, a seat in Congress in the May 10 national elections.

Arroyo's critics have accused her of wanting to use her position in the House as a platform to change the Constitution and become prime minister.

During her presidency, Arroyo had frequently said the gridlock arising from the presidency and parliament not agreeing on policy directions was holding back economic progress.

She tried repeatedly to change the Constitution, but her initiatives were blocked by the Senate, many of whose members, including Aquino at the time, harbored their own ambitions to the presidency.

Political analyst Ramon Casiple said Arroyo's fresh bid to change the Constitution could also be part of her efforts to avoid possible prosecution for alleged crimes committed during her time in power.

Aquino has said he intended to set up a Truth Commission to investigate and possibly prosecute Arroyo for alleged vote rigging, corruption and rights abuses.

A change to another form of government would derail the work of the investigative body, according to Casiple, from the Manila-based Institute for Political and Electoral Reform.

"It's just a matter of time before the... commission starts its work," he said.

And if Arroyo was hoping to thwart any plans by the Aquino administration to go after her, Lacierda said the move would not stop them from putting a closure to a number of issues that have haunted the past administration via the Truth Commission to be headed by former Supreme Court Chief Justice Hilario Davide Jr.

?Regardless of whether she files a bill or not with respect to charter change, the Truth Commission will be continuing and we don't see that as a threat. The filing of Cha-cha [Charter change] is not a threat as far as we're concerned,? said Lacierda.

Besides, Lacierda said the President made it clear that the commission would not become a ?witch hunt.?

?He [Aquino] wants to make sure that it will not be a witch-haunt. It will not appear as an act of vengeance on his part, hence, you need a person with integrity and with impartiality. That's the reason why you got Chief Justice Davide to ensure that there will be no witch haunt,? said Lacierda.

?Evidence will be gathered and those responsible will be prosecuted in accordance with evidence at hand,? he said.

Arroyo and her aides could not be reached for comment.