Malacañang said Mrs. Arroyo and De Castro would file within 10 days their respective answers to the complaint filed with the PET.
"The legal counsel of the President will await service of summons and will file an answer within the time required by the Presidential Electoral Tribunal," Presidential Spokesman Ignacio Bunye said.
"We are confident that we stand on solid legal ground," he added.
Housing and Urban Development Coordinating Council (HUDCC) Chairman Michael Defensor, who served as Mrs. Arroyo’s campaign spokesman during the campaign, said election lawyer Romulo Makalintal would represent the President before the PET.
Makalintal had represented Mrs. Arroyo during the congressional canvassing where the joint chambers declared her and De Castro as the winners of the May 10 vote last June 24.
Poe and Legarda last week asked the PET for a recount of the May 10 election results, alleging that the administration bets and their backers indulged in "massive and widespread electoral fraud" and manipulated votes in more than 118,000 precincts.
The PET issued a one-page resolution yesterday ordering Mrs. Arroyo and De Castro to file their reply within 10 days.
"The tribunal resolves to require Gloria Macapagal-Arroyo to file her answer within 10 days from notice hereof," the tribunal statement said.
Supreme Court spokesman Ismael Khan said the PET had found Poe’s complaint to be sufficient in form and substance for a likely full-blown hearing.
As soon as the court receives Mrs. Arroyo and De Castro’s reply, "it will deliberate and issue an order for the safekeeping of the ballots and the appointment of the hearing commission," Khan said.
Khan said it can be assumed that the PET would proceed with the recounting after giving due course to the protests.
"You might say that the Supreme Court found there is something to deliberate on, but whether there is merit or not in the complaint, that would depend on the presentation of evidence," Khan said.
"But of course, the answers will have to be evaluated first. We cannot really speculate on how the tribunal will decide and go through with the process," he stressed.
Khan said the tribunal would schedule the hearings of the case and would constitute itself into divisions or committees to allocate and distribute the task of recounting.
Asked when the hearing could be completed, Khan said: "If everybody sticks to the rules and no one files any dilatory or frivolous pleadings that are intended to delay the process, all of these things can be completed inside of a year."
Poe wanted a recount of the results of 118,339 polling precincts. He said the results of 10,554 precincts were erroneously reflected in the certificates of canvass (COCs) used in the counting by Congress.
Legarda, for her part, wanted a recount of 124,404 precincts, in which she claimed the results were erroneously counted in favor of De Castro.
Khan had stressed the filing of the electoral protest does not mean the recounting will be immediately conducted.
He had emphasized the process may be longer and exhaustive aside from being financially draining.
Under the Constitution, the Supreme Court sitting en banc shall act as the PET which shall be the sole judge of all contests relating to the election, returns, and qualifications of the President and Vice President.
The PET has to determine first if the petitions are sufficient "in form and substance." Otherwise, the petitions can be dismissed outright.
The petitioners will also have to pay the corresponding filing fees and the costs of the revision of ballots and election returns.
Once the revision of the contested election documents starts, the tribunal will continue to discharge its duty without any interruption within 180 working days.
The tribunal may also delegate the task of receiving evidence to a private lawyer who will serve as hearing commissioner.
At the hearings, the sworn statements submitted by the parties will constitute the direct testimonies of the witnesses. They will be subjected to cross-examinations.
Poe is a close friend of deposed President Joseph Estrada, who was replaced by Mrs. Arroyo in January 2001 over allegations of massive corruption.
Administration lawmakers have defended Mrs. Arroyo and belittled Poe and Legarda in filing their electoral protest.
A former Estrada ally also predicted Poe and Legarda will lose their election protest in the PET.
Former senator John Osmeña noted Poe filed the petition wanting to overtake Mrs. Arroyo’s winning margin from Cebu.
Poe’s lawyers estimated that after the revision of the election results by the PET, Poe would "recover" about 1.4 million to 1.5 million votes, enough to overtake Mrs. Arroyo’s 1.1 million margin.
Osmeña said Poe could never overcome the big margin Mrs. Arroyo enjoyed in his home province.
"It was Cebu that made the President win. Her huge margin of about one million votes there wiped out FPJ’s sizable lead in most of Luzon," Osmeña told an ANC interview Monday night.
The former senator, who lost his re-election bid under the administration slate, maintained Mrs. Arroyo garnered a wide margin from Cebu without any irregularity.
Opposition Sen. Aquilino Pimentel Jr., who won his second term under Poe’s ticket, expressed disbelief in Mrs. Arroyo’s huge margin in Cebu.
"Her (Mrs. Arroyo’s) 8-1 lead in Cebu was larger than her 6-1 majority in her home province of Pampanga. Cebuanos must (have loved) her very much," he said.
Cebu City Rep. Antonio Cuenco, for his part, disputed claims of fraud. He challenged critics to open up all the election documents covering votes from all the polling precincts of Cebu, assuring they would find nothing irregular. - With Marichu Villanueva, Jess Diaz, AFP