ABUJA-- Nigeria's presidential election was shaping up to be a contest between two veteran male politicians, but the candidacy of Oby Ezekwesili could change that.

Women have run for the presidency before but she is the most prominent Nigerian woman to challenge for the top job.

Ezekwesili is well known for leading the #BringBackOurGirls campaign to help free the 276 girls kidnapped from Chibok, northern Nigeria, in 2014. She has also served as the country's education minister and vice-president of the World Bank.

But come February's vote it will be a tough challenge to unseat incumbent President Muhammadu Buhari, 75, or beat the main opposition candidate, Atiku Abubakar, 72, who both have formidable party machines behind them.

The deadline to register for the election passed at midnight local time (23:00 GMT) on Sunday and at least nine candidates in all are thought to have submitted their papers.

At the weekend, Buhari was nominated by his All Progressives Congress (APC) and Abubakar beat a field of 11 others to become the flag bearer for the People's Democratic Party (PDP).

The two parties have supplied all of Nigeria's presidents since the end of military rule in 1999.

For Ezekwesili the men she is facing represent a "mediocre political class that bumbles from one crisis to another", as she told the meeting of the Allied Congress Party of Nigeria (ACPN), where her candidacy was declared.

She is setting herself up as the anti-establishment candidate, calling the politicians in charge of the country part of "an evil ruling class". And, in an Obama-like move, the ACPN is labelling her as the "hope" candidate.

Ezekwesili, who is 55 years old, is also trying to appeal to the youth of the country, saying that the people in charge do not understand the technological changes that are happening.

More than 50% of Nigerians are under the age of 30.

"How can a country gifted with millions of young, vibrant, brilliant people, be satisfied with just being [an] onlooker?" she asked.

The main opposition candidate is turning his fire onto the country's current leadership.

"The task to get Nigeria working again starts now," he tweeted after he won the PDP's nomination.

Abubakar, a powerful political figure and wealthy businessman, fought off a strong field including the leader of Nigeria's senate, Bukola Saraki, to get the nomination.

He served as vice-president from 1999 to 2007 and has made several attempts to run for the presidency, but has only once before secured the nomination of a major party.

He ran for Action Congress, a precursor to the APC, against the PDP's Umaru Yar'Adua and Buhari in 2007. Abubakar gained 7.5% of the vote but complained of widespread fraud.

Buhari is under a lot of pressure as he runs for re-election.

He won the 2015 election, beating incumbent President Goodluck Jonathan, as the change candidate, but he has left a lot of people disappointed.

The country slipped into recession in 2016 and economic growth has been slow since then. Nigerians are also questioning whether the government has got a grip on insecurity in the country.

But the president argues that progress has been made on the economy, saying that his government has "checked the slide [into] anarchy on the security and economic fronts".

More than 270 girls were kidnapped by militant group Boko Haram from a school in the north-eastern town of Chibok in 2014.

A massive social media campaign under the hashtag #BringBackOurGirls brought the story to international attention.

Ezekwesili was one of its leading voices.

Many of those who were taken have now been released, but more than 100 of the kidnapped schoolgirls are still being held and their whereabouts are unknown.