MANILA - Former Senate President Juan Ponce Enrile said Wednesday mistakes in the draft federal charter proposed by President Rodrigo Duterte's Consultative Committee (ConCom) compelled him to seek a Senate comeback.

The 94-year-old former legislator surprised the public when he filed his certificate of candidacy last week, personally appearing at the Commission on Elections.

In a forum in Quezon City, Enrile, a lawyer, said during his time out of government, he studied the ConCom's draft and found a lot of "mistakes" that he said would add to the people's burden.

"Ang tunay na nag-udyok sa akin na tumakbo ulit—hindi ko pinlano ito eh—ay nung pinag-aralan ko 'yung panukalang saligang batas na ginawa ng ConCom, nakita ko na maraming mali," he said.

(What really prompted me to run again- I did not plan this- is that when I studied the proposed federal charter drafted by the ConCom, I saw a lot of mistakes.)

The proposal, written by the 25-member committee that included former Supreme Court associate justices, was submitted to Duterte in July.

The draft seeks to change the country's form of government into a federal-presidential model with 18 federated regions, a shift from the unitary form of government Duterte had promised during the 2016 presidential campaign.

• Charter change body wraps up work on draft federal constitution

Enrile pointed out that the committee failed to give an exact figure of how much the shift to federalism would cost, considering that this will be funded by taxpayers.

He also warned about the possible "vast and absolute dictatorship" if the ConCom's draft is adopted.

"Kung may mangyari sa bansa, sa presidente, ano ang remedyo natin? Lahat ng kapangyarihan ng gobyerno—judicial, legislative, executive—hahawakan ng transition commission," he said.

(If anything happens to the country, the president, what will be our remedy? All the power in government - judicial, legislative, executive- will be held by the transition commission.)

"Kung may masasaktan sa desisyon ng transition commission, saan sila pupunta? The proposal has established a vast and absolute dictatorship in this country [in the transition period]," he added.

(If someone gets hurt by the decision of the transition commission, where will they go?)

Under the ConCom's proposal, the "Transition President" will have the powers of the President under the federal charter until the transition period expires.

• READ: Con-Com's final draft of PH federal constitution

The Transition President will also chair the Federal Transition Commission which will be composed of 10 regular members that he or she will appoint, among others.

The commission, the ConCom's draft proposes, will be mandated to "exercise all powers necessary and proper to ensure a smooth, speedy, and successful transition."

Enrile is among lawmakers tagged in the diversion of discretionary funds into bogus NGOs linked to businesswoman Janet Lim Napoles. He is still facing trial at the Sandiganbayan.

He was detained in 2014 but was allowed by the Supreme Court to post a P1-million bail due to "instability of his health and his advanced age."