MANILA, Philippines -- The Japan-Philippines Economic Partnership Agreement (JPEPA) has come closer to being ratified after 12 senators urged concurrence of the controversial treaty, Senator Miriam Defensor-Santiago said Tuesday.

The resolution for concurrence, which is going the rounds among the senators now, is scheduled for sponsorship tomorrow.

It was actually signed by 13 senators but one of them, Joker Arroyo, asked to explain his signature, said: "I withheld my concurrence, meaning, I did not concur with the treaty because the two countries could not agree on the side agreement which was intended to resolve or cure the disagreements between the two countries."

But Santiago, in an interview with reporters, said the issue of the JPEPA’s constitutionality has already been resolved because Japan has agreed to the side agreement providing a complete list of all the provisions of the Philippine Constitution which allows economic activity only to Filipinos or Filipino-owned corporations at the level of 60, 70, or even 100 percent.

"In any event, there is no more debate on constitutionality because the Japanese foreign minister has authorized the Japan ambassador here to enter into an exchange of notes presumably with Secretary Alberto Romulo of DFA [Department of Foreign Affairs] so that all constitutional provisions in our Philippine Constitution that conflict with JPEPA will be deemed to be dominant or superior to any JPEPA provision," she said.

A list of signatories from Santiago’s office showed only three senators -- Edgardo Angara, Juan-Ponce Enrile, and Manuel Lapid -- without reservations.

Those who signed with reservation were Santiago, Senators Manuel Roxas II, Richard Gordon, Ramon Revilla Jr., Rodolfo Biazon, Miguel Zubiri, Jose Estrada (with serious reservation), Francis Pangilinan (without prejudice to section 24, paragraph 4), and Aquilino Pimentel Jr., and Arroyo.

Santiago is expected to present the side agreement on Wednesday.

"And since the constitutional provisions over which I was very adamant for the past year have already been accepted by Japan, I have no more problem with it as a constitutional law scholar," she added.

"In any event, now we will no longer have to debate it. So my hopes are high that we will be able to get the two-thirds vote. Two-thirds of 23 should be about 15 or 16,” she said, adding that the needed vote may be achieved even “at the committee level alone.”

Santiago said she sees the Senate ratification of the treaty in September after floor debates.

Asked to describe how the process is moving, she said: "Well it is edging toward ratification and I hope I will be able to convince them tomorrow because we lose a lot in terms of economic benefits if we do not concur."

Santiago says Japanese foreign direct investment and increased earnings from exports will all go to other Southeast Asian countries if the Philippines does not ratify the JPEPA.

"We'll be the odd man out," she said.