By Senan Murray
BBC News, Abuja
It would seem that Nigeria's Independent National Electoral Commission (Inec) may not have learnt many lessons from the chaos that marred last Saturday's state elections.
The security forces hope to avoid a repeat of last week's violence
On the eve of the poll, Inec chairman Maurice Iwu announced on national television that ballot papers to be used in the elections had yet to arrive in Nigeria, raising serious logistical doubts about the exercise.
It would be hard to distribute millions of ballot papers across the vast country with very poor road network.
But that is just one of the many hurdles for Inec to negotiate if it is to conduct free and fair elections in Africa's most populous nation.
After spending over six months fighting in courts to win a spot on the ballot, Vice-President Atiku Abubakar is finally running.
But many analysts believe he and the opposition candidates have little chance.
They point to the "incumbency factor" and the massive electoral machine of the governing People's Democratic Party (PDP) and conclude that it is bound to be an easy win for Umaru Musa Yar'Adua, the reclusive Muslim governor of north-western Katsina State, backed by the outgoing president.
And with the opposition's so-called "grand alliance" in tatters, the PDP appears set to secure a third consecutive term in office.
Some 18 opposition parties earlier this week threatened to boycott the presidential poll if the central government and Inec failed to correct "the irregularities of last Saturday's elections".
But neither of the two main opposition contenders, Mr Abubakar of the Action Congress (AC) and Muhammadu Buhari of the All Nigeria People's Party (ANPP) were willing to step aside for the other.
The PDP is the most obvious beneficiary of the failure to agree.
Nigerians hope they won't be taken for a ride at the polls
"The collapsed alliance could have made some difference. Sadly, even the opposition parties don't seem well organised," says Mohammed Haruna, journalist and public affairs analyst.
The AC says it is going into the poll for the sole purpose of gathering evidence to challenge the outcome in court.
"Under the Nigerian law, you cannot challenge the outcome of an election if you did not participate in the election," Mr Abubakar's spokesman Garba Shehu told the BBC News website.
He admits that the opposition does not stand a chance against the ruling PDP.
"You can't win against the guy who will write the result," he says.
President Olusegun Obasanjo's description of the election as "a do-or-die affair for the PDP" has led many Nigerians to believe that the ruling party is set to rig Saturday's vote.
"When the president himself has come out to say the elections will be a do-or-die affair, what else can you expect?" says opposition politician Yahaya Usman in the central Nigerian city of Jos.
60m registered voters
120,000 ballot boxes
360 House of Representative seats to be elected
109 Senate seats to be elected
24 presidential candidates
Main contenders: Atiku Abubakar for the AC, 60-years-oldMuhammadu Buhari, ANPP, 64Umaru Musa Yar'Adua, PDP, 55
Polls open 1000-1700 (local time) (0900-1600 GMT)
To avoid a run-off, a candidate needs highest number of votes overall and at least 25% of votes in 24 of the 36 states
Mr Haruna agrees that with the governing party's "desperation to hang on to power at all cost", Nigerian voters should be ready for more violence and irregularities in the presidential poll.
"The scale of violence and irregularities is most likely to be worse because the stakes are higher. Soldiers have formed roadblocks across the country.
"People are on edge seeing so many guns on the streets. One must also not forget that these soldiers are loyal to the government in power and the government in power is a PDP government."
Mindful of the late arrival of ballot papers at polling stations across the country during last Saturday's voting, Mr Iwu says voting in the presidential poll will be delayed by two hours and close at 1700 local time (1600 GMT) rather than 1500.
He admitted that the 65m ballot papers, which are printed abroad, had not arrived in Nigeria less than 24 hours before the polls were due to open.
Election workers will be working flat out to be ready
Last Saturday's governorship and state legislative elections were marred by violence, ballot-box snatching, under-aged voting and violent protests, with the governing PDP winning 27 states out of the 34 announced.
Elections were postponed in two states because of the problems.
But Inec says the mistakes of last Saturday will not be repeated.
"There were loopholes that we observed in last Saturday's elections. I believe that we have been able to plug all those loopholes," Mr Iwu, the Inec chairman, told reporters in Abuja.
In Africa's most populous country, a party's performance at the state elections is usually an indication of its chances in the presidential poll.
Unlike in 2003 when religion played a very important role in the election between President Obasanjo, a southern Christian and Mr Buhari, a northern Muslim, this time around, religion is not an issue, at least, not at the national level with all three major contenders coming from the Muslim north.
Violence marred last week's state polls
In the presidential election, Nigerians are no longer talking about poverty, healthcare, education and the country's poor infrastructure, as they seem more concerned about vote rigging.
"At this stage, no-one is interested in the issues any more, not because the issues no longer count, but because the concern about whether or not the vote of Nigerians will count is uppermost now," says Abuja taxi driver Sola Ajishafe.
If the election is successful, it would be the first transfer of power from one civilian regime to another in a country that has seen about three decades of military rule in its 46-year history.