The Independent National Electoral Commission, INEC, is conducting four bye-elections in Katsina, Bauchi, Kogi and Cross River States.
The elections commenced on Saturday morning in all four states.
In Kogi, the Resident Electoral Commissioner, Professor James Apam, said four ad-hoc staff were deployed to man each of the 310 polling units in Lokoja and Kogi/Koton-Karfe Local Government Areas.
Meanwhile, in Katsina, the election is being conducted in 1,577 polling units spread across the 12 Local Government Areas that make up the katsina north senatorial district.
Six candidates from six political parties, including two brothers are contesting the election.
According to INEC, over 800,000 electorates are expected to vote in the state.
It also noted that 700 ad-hoc staff were deployed to 117 polling units in the Obudu constituency of Cross River.
Four candidates are contesting to fill the vacancy left in the House of Assembly following the death of Stephen Ukpukpen who had previously occupied the seat.
And in Bauchi, voting is ongoing although voter turnout so far has been low.