The lawmaker made the revelation while reacting to President Muhammadu Buhari's controversial comment about directing security operatives to be "ruthless" in dealing with ballot box snatchers who attempt to disrupt the election.
"Anybody who decides to snatch boxes or lead thugs to disturb it, maybe that's the last unlawful action you'll take. I really gave the military and the police order to be ruthless," President Buhari said during his own party's caucus meeting on Monday.
Melaye noted security operatives swore an oath of allegiance to the constitution and not the president, warning that any operative that violates the constitution in carrying out the president's orders will face the nation's laws.
He said, "The unpresidential statement by the president yesterday as far as I'm concerned is a suspension of the constitution of the Federal Republic of Nigeria.
"And I want to say that every military man, every police (officer) that took oath of allegiance did not take the oath to Muhammadu Buhari but to the constitution of the Federal Republic of Nigeria.
"We in the PDP are ready, we've purchased secret cameras and any soldier, police man or paramilitary man who will abuse his oath of office in being used by the APC to unleash terror on Nigerians, we will record you."
Melaye urged the military to be professional and warned President Buhari that Nigerians are ready to vote him out of office.
He said, "Maybe some of you have a network problem with God, I have no network problem with God, whenever I call upon him, he answers me and he told me that Atiku will be President of the Federal Republic of Nigeria.
"Government is not owned by those in government but by the people of the Federal Republic of Nigeria, and on Saturday, we're going to prove to the APC and President Muhammadu Buhari that the election is not between Atiku and Buhari but between Buhari and the masses of the Federal Republic of Nigeria. We shall not allow rigging and we shall not allow intimidation."
The PDP's national chairman, Uche Secondus, also slammed Buhari's comment as a "death sentence on all voters of Nigeria" that should not be obeyed by security operatives.
Atiku slams Buhari for comment
While also condemning President Buhari's comment during the Tuesday meeting, the PDP's presidential candidate, Atiku Abubakar, urged security operatives to not carry out any unlawful orders even if they come from the office of the Commander-in-Chief.
"In military, commanders and officers are not bound to execute orders that are manifestly unlawful. This is the law, this is the tradition in the military.
"If you're a professional military commander, officer and soldier, and also a policeman, you're not bound to execute an order that's manifestly unlawful no matter who issues that order," he cautioned.
Atiku and Buhari are favourites to win the 2019 presidential election which was recently rescheduled from its initial February 16 date to February 23.
71 other candidates are listed to contest in the election even though some of them have dropped out and declared support for Atiku or Buhari.
The leading candidates in the chasing pack are Kingsley Moghalu of the Young Progressive Party (YPP), Omoyele Sowore of the African Action Congress (AAC), and Fela Durotoye of the Alliance for New Nigeria (ANN).