The Senate has summoned the Chairman of the Independent National Electoral Commission, Prof. Attahiru Jega, to appear before it.
The summon was extended to Jega on Tuesday.
He is to explain the reason for the postponement of the general elections to the senators.
Jega is to appear before the Senate on Wednesday.
The Senate has also asked Jega to appear before it with the card reader machines for a demonstration of how it functions.