Nigeria's president has formally declared that he will seek a second term of office at next year's general election, just a day after a suicide bomber killed nearly 50 people in the country's northeast.

Goodluck Jonathan has been head of state of Africa's most populous nation, leading economy and top oil producer since 2010, when he took over following the death of President Umara Yar'Adua, winning elections in 2011.

"I, Goodluck Ebele Azikiwe Jonathan, have accepted to present myself on the platform of the PDP," Jonathan told supporters of his Peoples Democratic Party at a mass rally in the capital Abuja on Tuesday.

His supporters took out four-page newspaper advertisements on Monday, calling for Nigerians to "be a witness to history" and saying Jonathan's candidacy was "in response to Nigerians' demand".

"Nigerians endorsed Goodluck Jonathan for continuity," the adverts ran, claiming that more than 17.8 million had so far endorsed his candidacy.

But for the country's main opposition All Progressives Congress (APC), Jonathan's tenure has been far from a success, particularly on security and his perceived failure to tackle Boko Haram.

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The armed group, which claims to be battling Western influence and wants to form an Islamic state, was blamed for Monday's deadly suicide bombing at a school assembly in Potskum, in Yobe state.

Al Jazeera's Ahmed Idris, reporting from Lagos, said Jonathan's administration had been losing support due to its failure to tackle Boko Haram violence, corruption and problems in the power sector.

"The attack that happened on Monday underlines the challenges the Jonathan administration has faced over the past years," he said.

"Over the past four years we have seen Boko Haram grow bolder and take more territory. The challenge to the group seems to be fading and the Nigerians are not happy with this."

Violence by Boko Haram has claimed more than 10,000 lives in five years and Jonathan has in recent months seen the apparent loss of more than a dozen towns to fighters in the far northeast.

Jonathan also came under fire for his lacklustre response to the mass abduction of 276 schoolgirls in April and his decision to be seen partying 24 hours after the kidnapping.

According to reports, 219 girls are still missing.

In his speech in Abuja on Tuesday, Jonathan addressed the issue of Boko Haram and the abductions.

"This has cast a dark cloud over our nation, but we will surely win the war on terror," he said.

"We will surely get our daughters freed and defeat terror in our country."

Source: Al Jazeera and agencies