Who may contest the election of the President or the Vice-President?

Rule 14 of the PET Rules provides:

Rule 14. Election Protest. Only the registered candidate for President or for Vice-President of the Philippines who received the second or third highest number of votes may contest the election of the President or the Vice-President, as the case may be, by filing a verified petition with the Clerk of the Presidential Electoral Tribunal within thirty (30) days after the proclamation of the winner.

Pursuant to this rule, only two persons, the 2nd and 3rd placers, may contest the election. By this express enumeration, the rule makers have in effect determined the real parties in interest concerning an on-going election contest. It envisioned a scenario where, if the declared winner had not been truly voted upon by the electorate, the candidate who received that 2nd or the 3rd highest number of votes would be the legitimate beneficiary in a successful election contest. (Poe vs. Arroyo PET Case No. 0002, March 29, 2005)