Nigeria's President Muhammadu Buhari said Monday he had ordered the police and military to be "ruthless" with vote-riggers, as preparations were made for rescheduled elections.
Presidential and parliamentary elections were put off just over five hours before polls were due to open on Saturday, causing widespread anger.
New polls have been rescheduled for this Saturday, while governorship and state assembly elections have been pushed back to March 9.
At an emergency meeting of his ruling All Progressives Congress party (APC) in Abuja, President Buhari said he intended to make sure the rescheduled ballot proceeds without a hitch.
"I do not expect anybody to make any disturbance," he told senior party members. "Anybody who decides to snatch (ballot) boxes or use thugs to disturb it (the vote), maybe this will be the last unlawful action he will take."
Mr Buhari, 76, said he had ordered "the military and the police to be ruthless" to ensure all Nigerians can vote for their chosen candidate.
"I am going to warn anybody who thinks he has enough influence in his locality to lead a body of thugs or snatch (ballot) boxes or to disturb the voting system, he will do it at the expense of his life," the President added.
Both the APC and the main opposition Peoples Democratic Party (PDP) have been accused of wanting to rig the result, notably by buying biometric voter identity cards.
The Independent National Electoral Commission (INEC) blamed the last-minute delay on logistical difficulties in the distribution of election materials, as well as sabotage.
Elections have been delayed before in Nigeria: in 2015, there was a six-week postponement on security grounds linked to the Boko Haram conflict in northeast Nigeria.
In 2011, the election was halted after it had already begun due to problems with the non-delivery of ballot papers, results sheets, and other voting materials.
This year's election is the sixth in the 20 years since Nigeria returned to civilian rule after decades of military government.
Some 84 million voters are registered.