The electoral office signified a breakaway from its previous conclusion on the controversial senatorial primary.
Mr Lawan has been at the National Assembly since 1999.
The senate president commended security agencies for the recent improvement of security in the country.
Minority Leader of the Senate, Phillip Aduda, disclosed the ultimatum to press after a mass walkout by his colleagues.
Mr Machina is seeking legal redress following Mr Lawan’s attempt to claim the ticket after losing his bid for the party’s presidential slot.
The electoral body in a statement asked Mr Machina to go to court over his dissatisfaction with the refusal of APC to submit his name.
The senators are investigating corruption allegations brought against the former CJN by 14 justices of the apex court.
INEC will take the lion’s share of the blame if this democratic experiment dies.
Mr Machina was certified as the winner of the primary, but he still expects the ruling party to double down its plot to trade his mandate for the Senate President.
If confirmed, Mr Shehu would replace Elias Mbam, who resigned to pursue his gubernatorial ambition in Ebonyi.
