Nigerians went out to vote under tight security on Saturday in a ballot delayed by administrative bungling and marred by a deadly bomb attack hours before polling stations opened.
The setbacks have added to questions over whether Africa's giant, with more people than Russia, can hold its first credible elections since military rule ended 12 years ago.
Saturday's parliamentary vote, delayed a week because ballot papers failed to arrive across much of the country, will be followed by the more important presidential election on April 16, with governorship polls in 36 states on 26 April.
Although electoral officials failed to turn up on time in some places and materials were still arriving as voters gathered, initial signs were that preparations were better in much of Nigeria than during the first attempt.
"We want to show the rest of the world that we are ready for democracy," said Mukaila Odukoya, a 45-year old trader, in the Obalende district of Lagos as people clamoured to find their names on the voter register at a polling booth.
"This one is going to be far, far better than the past. This is going to be one man one vote. It is not going to be easy for people to buy ballot papers, though they are trying," Odukoya said, proudly clutching his voter registration card.
Security was tightened nationwide after a bombing killed at least 10 people late on Friday at an office of the Independent National Electoral Commission (INEC) in Suleja, on the edge of the capital Abuja. There was no claim of responsibility.
"Nigerians must remain resolved not to allow the perpetrators of this dastardly act to achieve their aim of scuttling the aspiration of Nigerians for free, fair, peaceful and credible elections," said Attahiru Jega, the academic who heads INEC and has pledged to hold a fair election for once.
People headed for polling stations across the country of 150 million, which stretches from the oil-producing mangrove swamps and teeming cities near the coast to the dustblown fringes of the Sahara desert.
Under procedures to try to stop cheating, up to 73 million voters must first register from 8am before the actual voting starts at 12.30pm.
The ballot was called off last Saturday after voting slips and other materials failed to reach most of Nigeria. Adding to the confusion was the fact that voting had started in some areas by the time it was cancelled.
Another delay will affect voting in places, although it is due to take place in 90 per cent of constituencies. The ballot was postponed again in Suleja after the bombing.
Amid the rubble outside the election office, armed guards appealed to angry residents to keep calm.
"I want to vote. It is our future we are trying to keep safe," said computer engineer Tunde Dasilva.
Seats in the assembly are fiercely contested by candidates who stand to win a package whose benefits alone amount to more than US$1 million a year.
Isolated bomb attacks have hit campaign rallies, violence blamed on a radical sect has affected the remote northeast and sectarian clashes have erupted in the centre of a nation roughly split between a Muslim north and Christian south.
Nearly 100 people have been reported killed in the election run-up.
President Goodluck Jonathan is widely expected to win the presidential poll, but his ruling People's Democratic Party could see its parliamentary majority reduced.
The PDP holds more than three-quarters of the 360 seats in the House of Representatives and of the 109 in the Senate.