House of Representatives minority leader Francis Escudero and opposition Rep. Gilbert Remulla told foreign correspondents that the case will be filed in July with at least the 79 supporters needed to endorse and send it to the Senate for trial. The House is dominated by Arroyo's allies.

Escudero said the 51 lawmakers who supported a failed impeachment bid last year on charges of alleged vote rigging and corruption by Arroyo would be joined by disgruntled members of the majority.

After pre-empting an alleged coup last month, Arroyo declared a week-long state of national emergency, cracked down on protests, filed rebellion charges against alleged coup plotters and raided a critical newspaper.

At the center of the poll fraud controversy are alleged wiretaps of her supposed phone conversations with Virgilio Garcillano, an election commissioner, about ensuring a million-vote victory in the 2004 election. Arroyo has denied any wrongdoing, saying she won the election fairly.

``There is only one mechanism to make the president accountable, and that is through impeachment,'' Escudero said.

He claimed two people would testify about participating in an alleged break-in at the House, allegedly to tamper with election returns kept there.

He said other witnesses include former election officials and personnel deputized for the 2004 elections who claim they were ordered to help in cheating.