MANILA, Philippines (3rd UPDATE) - Senator Juan Miguel Zubiri is expected to announce his resignation from the Senate on Wednesday after new witnesses to fraud in the 2007 elections cast doubt on his mandate.



A source close to Zubiri told ABS-CBN News the senator will make his announcement in a speech at the Senate this afternoon.



Zubiri will supposedly resign to spare the institution from further controversies brought about by allegations of fraud.

Minutes before Zubiri's announcement, Sen. Panfilo Lacson confirmed that Zubiri would announce his resignation.



Zubiri's lawyer, George Garcia, did not answer queries on the matter. He only said the speech will revolve around “Zubiri’s gratitude for the people who helped him.”



His family and close friends will also attend this afternoon’s session.



Lawyer Aquilino 'Koko' Pimentel III filed an election protest after Zubiri snatched the 12th and last senatorial post in 2007.



Pimentel's protest is still pending before the Senate Electoral Tribunal.



New witnesses, including suspended Autonomous Region in Muslim Mindanao (ARMM) Governor Zaldy Ampatuan and former Maguindanao election supervisor Lintang Bedol, recently came out saying they were instructed by Malacañang to pad votes for Zubiri in 2007.



Ampatuan, an accused in the Maguindanao massacre case, also revealed he was ordered to cut the votes for opposition bets Panfilo Lacson, Noynoy Aquino, and Alan Peter Cayetano



Zubiri, who ran under the administration ticket, won the post by a slim margin of around 21,000 votes over Pimentel, who ran under the opposition. – with a report from Ruby Tayag, dzMM