The lawmaker alleged that Obasanjo, Babangida, and Abdulsalami are working against Buhari's anti-corruption war.
He alleged that the three past leaders are already searching for Buhari's successor ahead of 2019 elections, describing the act as "conspiracy against good governance."
Speaking in an interview with Punch on Monday, August 7, Kassim said Obasanjo, Babangida, and Abdulsalami are working against Buhari's anti-corruption war.
"I debunk media reports of purported hunt for the replacement of President Muhammadu Buhari by three former military presidents," the lawmaker, who is also the national chairman of the Democratic Youth Congress, said.
According to him, Buhari never confided in any of the ex-leaders about his future political plans.
Kassim added that these leaders "ignominiously mismanaged" Nigeria, thereby lacking the moral standing to chart a political course for the country.
He said the alleged search was intended to "cause political disharmony in the polity."
"What have Obasanjo, Babangida and Abdulsalam Abubakar bequeathed to this country as leaders, if not corruption, nepotism, underdevelopment and values laced with mutual distrust and suspicion which has further compounded our journey to prosperity as a nation," Kassim said.
"Enough is enough. We Nigerian youths have allowed such leaders to mortgage the future of this country.
"We, Nigerian youths, would henceforth use any civil and political will to resist such attempt by past leaders to … determine the common destiny of this great nation."
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Ailing Buhari has been under criticisms for being away from the country for months without openly telling Nigerians the nature of his ailment.
Critics, especially members of the opposition, Peoples Democratic Party (PDP) have been mounting pressure on the President to resign.