Buhari won re-election for a second term after polling a total of 15,191,847 votes to beat the PDP's candidate, Atiku Abubakar, who gained 11,262,978 votes in the February 23 election.
While speaking at the opening session of the PDP's National Executive Committee (NEC) meeting in Abuja on Wednesday, March 20, Saraki said even the ruling All Progressives Congress (APC) is ashamed of Buhari's victory because of how the election was conducted.
The former Kwara State governor accused the APC of being desperate to hold on to power and condemned the militarisation of the electoral process that led to Buhari's victory.
He said, "If anybody believes that it is a loss to PDP, it is a loss to the country that history will not forgive.
"We said it many times here, that the worst to do is to do an election that as a country Nigeria will not be proud of.
"We have done an election that no doubt anybody and even those that think they have won are ashamed of. I think it is a shame to the country and to those that were given that responsibility to do."
Atiku has branded the election the worst in Nigeria's history and officially filed a petition against Buhari's victory before the Presidential Election Petitions Tribunal.
Ex-US Ambassador condemns electoral process
In an article for the Council on Foreign Relations, John Campbell, a former United States Ambassador to Nigeria, said the election sets a bad example for democracy in Africa.
Describing the election as "bad news for democracy", he said it was marred by historically low turnout and credible allegations of rigging.
However, despite acknowledging that the process was riddled with several malpractices, Campbell believes Atiku's decision to contest the result in court will most likely fail.