"If we do that, we will never finish this canvass," he said.
He said there are more than 200,000 ERs and examining these documents could take years.
Besides, scrutinizing the election return is the job of the Supreme Court sitting as the President Electoral tribunal, he added.
Lawmaker-supporters of opposition standard-bearer Fernando Poe Jr. who are sitting in the joint Senate-House canvassing committee have been trying to convince the panel to go down to the ERs whenever they discover signs of fraud on the provincial-and city-level certificates of canvass (COCs) that it is tabulating.
The opposition is invoking Section 17 of the canvassing rules which allows a resort to the ERs.
But the committee, which is dominated by allies of President Arroyo, has been voting down every request the opposition presents, prompting the minority to accuse the majority of hiding something.
Deputy Speaker Raul Gonzalez, who is presiding over the canvass jointly with Senate Majority Leader Francis Pangilinan, said allowing the examination of just one ER could "open a Pandora’s box."
"It will also open the floodgates to the security of all election returns," he said.
Based on its tally of votes as reflected in the ERs, Poe’s camp claims that the movie actor defeated Mrs. Arroyo by about 500,000 votes. The actor’s supporters are expected to release the results and details of their tabulation this weekend.
The unofficial tabulation of COCs showed that the President won over her opposition rival by more than one million votes. The same COCs are being used in the congressional canvass.
The opposition was expected to again test the limit of the committee’s obstinacy in the opening of the ER’s last night when the COC from Cebu comes up for canvassing.
Mrs. Arroyo took a huge margin of nearly one million over Poe in Cebu, more than enough to wipe out the actor’s lead in most of Luzon.
The Poe camp claims it was cheated in several provinces, including Cebu, Bohol, Iloilo, Maguindanao, Lanao del Sur, and Sulu.
Presidential Legislative Liaison Officer Gabriel Claudio, who was Mrs. Arroyo’s campaign manager and who monitors the congressional canvass every day, told reporters yesterday that his candidate "is now out of the woods, out of the deficit column."
He said starting with COC No. 119 from Iloilo that was canvassed on Wednesday night, the President would lead all the way until the last COC, No. 176 from Cotabato City, is tallied.
When the tabulation is ended, Mrs. Arroyo would have a margin of more than one million votes over Poe, he said.
Drilon also said the joint canvassing committee is still on schedule in its tally.
"We can still finish the canvass within the week provided the opposition agrees to work on Saturday. I appeal to their sense of patriotism, let us work this coming Saturday so we can wrap up the canvass," he said.
He conceded that the opposition can question the Saturday tabulation plan since the canvassing rules provide that the joint committee will do its job only from Monday to Friday.
He said if the committee is able to finish the vote count this weekend and approve its report on Monday, the joint session of Congress can resume on Tuesday.
"We can tackle the report from Tuesday through Friday or Saturday next week and then proclaim the winners," he said.