On Wednesday, legislator Rodante Marcoleta said he had endorsed the complaint filed by private lawyer Oliver Lozano for "betrayal of public trust", one of several grounds for impeachment.
A committee now has to decide whether the complaint has sufficient substance to be referred to the 250-member parliament, where it would need the support of one-third of members to be passed on to the Senate.
With that support, the Senate or upper house, would transform itself into an impeachment court to hear the complaint.
Analysts said the complicated process was unlikely to go far as Arroyo had significant allies in parliament.
Marcoleta, who belongs to a fringe political party, said he had endorsed the impeachment move because he had "verified the complaint and have found the same to be sufficient in form and substance".
"Today, my family is once again called to sacrifice our personal happiness to allow me to serve best as president of our country"
Gloria Macapagal Arroyo,
He said the impeachment process was the "only legitimate and constitutional way" to resolve the crisis which arose after Arroyo admitted late on Monday that she had telephoned an unidentified election official during last year's presidential vote.
Arroyo, however, denied charges that she had been trying to rig the election, saying the call was a clumsy bid to protect her vote amid a slow count.
Opposition Congressman Francis Escudero said Marcoleta's endorsement of the hastily filed impeachment complaint could be a ploy to kill any moves to oust the president as once a complaint was endorsed, parliament would be barred from accepting any more impeachment complaints for a year.
If the impeachment bid failed, there would be no other constitutional way to remove Arroyo, he said.
The last time the Philippines tried to impeach a sitting president was in 2000, when Joseph Estrada was accused of looting public coffers of some $80 million.
The impeachment hearings broke down after Estrada allies in the Senate blocked presentation of crucial evidence against him, plunging the country into political turmoil.
Massive street protests that followed snowballed into a "people power" revolt backed by the military that ousted Estrada in January 2001. He was replaced by Arroyo, then his deputy.
Estrada is under house arrest while being tried.
Arroyo moved dramatically on Wednesday to reduce pressure on her government from graft allegations, saying her husband had agreed to leave the country.
She did not say how long her husband, Jose Miguel and known widely as Mike, would remain abroad.
Arroyo denies the election
rigging charges against her
Opposition lawmakers have said he, the couple's son and other family members were involved in payoffs from gambling syndicates, but nothing has been proved.
Her husband has also been accused by the opposition of helping Arroyo try to fix the results of last year's election in telephone conversations with an election official.
"Today, my family is once again called to sacrifice our personal happiness to allow me to serve best as president of our country," Arroyo, her voice cracking with emotion, told a business forum in Manila.
"My husband has volunteered to go abroad. I mention this here today because I want to signal to everyone that nothing can stop my administration from implementing ... our reform agenda."
Rex Robles, a security analyst, said that by agreeing to let her husband leave she appeared to be weakening under pressure from her critics.
"She has become desperate in response to building pressures for her to quit," he said. "Obviously, her advisers wanted to clear a ray of sunshine in the midst of these scandals of election cheating and illegal gambling payoffs.
"But I think the sky has even darkened and threatening a heavy downpour or a storm."