Prof Mahmood Yakubu, the Chairman of the Independent National Electoral Commission, INEC, has threatened to go to court.
He said the allegation that he rigged the presidential election could lead to a lawsuit.
The electoral chief issued a reply to the Peoples Democratic Party, PDP, after the leadership, on Friday, asked him to resign.
The opposition charged the police and the Department of State Services, DSS, to investigate the chairman over alleged manipulation of election results.
A statement by Yakubu’s Press Secretary, Rotimi Oyekanmi said the call was misplaced and challenged the PDP to prove its claims in court.
The spokesperson wondered why the party did not provide evidence to back up “the spurious allegations”.
Oyekanmi said the PDP also did not give evidence of how Yakubu sabotaged the uploading and transmission of results from polling units.
The aide maintained that the INEC “does not rig elections”, stressing that the Bimodal Voter Accreditation System, BVAS, “has ensured the integrity of the electoral process”.
Oyekanmi remined the PDP that it rejected the outcome of the February 25 poll and should toe the path of honour by pursuing its case until judgment is delivered.
“Canvassing the same issues the party intends to plead in court on the pages of newspapers and calling for the resignation of the INEC Chairman is like putting the cart before the horse.
“The PDP is hereby reminded that making libelous allegations against the person of the INEC Chairman is actionable,” he added