All territory currently controlled by Boko Haram could be retaken by the Nigerian army within a month, President Goodluck Jonathan has claimed, but a country expert told Christian Today that the group is likely to prove "tough to dislodge".

In an interview with the BBC, Jonathan said that the Islamist militant group are "getting weaker and weaker by the day".

"I'm very hopeful that it will not take us more than a month to recover the old territories that hitherto have been in their [Boko Haram's] hands," the president said.

Christian Solidarity Worldwide Nigeria's representative said that things are looking positive for the fight against Boko Haram. "There is no doubt that receiving upgraded weaponry has rejuvenated the Nigerian Armed Forces," the source said.

"The fact that Boko Haram can no longer retreat and regroup in neighbouring francophone states as it has done in the past may assist in ensuring its military defeat within that time frame. However the group has retreated to its strongholds and may be tough to dislodge."

Jonathan has been criticised for his government's slow response to the crisis, and was forced to postpone the Nigerian election by six weeks earlier this year. Head of the Independent National Electoral Commission, Attahiru Jega, announced that there were not enough troops available to protect voters after Boko Haram began stepping up attacks in the lead up to the original date of February 14.

The president told the BBC that authorities had "under-estimated" the militants.

National security has been a key part of the agenda in the lead up to the elections, now due on March 28. Tearfund's country representative for Nigeria, Danladi Musa, who is based in Jos, said that insecurity would be the biggest issue for voters.

"People are more likely to vote for a presidential candidate who will address the security concerns of Nigeria at this moment," Musa said. But religious tensions have also been simmering; Jonathan is a Christian, while his main opponent, Muhammadu Buhari, is expected to harness much of the Muslim vote.

Jonathan's claim that all Boko Haram controlled territory could be retaken so soon could well be a pre-election tactic to increase votes. However, together with troops from neighbouring Chad, Niger and Cameroon, the Nigerian army has been making gains against Boko Haram in recent weeks.

At the beginning of this year, the group controlled 20 local government areas – a territory Reuters described as the size of Belgium. On Tuesday, however, Nigeria's army said rebels had been driven out of all but three local government areas, all of which are in Borno state. Boko Haram is no longer operating in Yobe or Adamawa states.

African troops liberated the northern Nigerian town of Damasak in Borno state last Saturday, a victory that was considered to have turned the tide against the jihadi insurgency.

"Troop morale is sky-high," Niger force leader Colonel Toumba Mohamed said following the offensive.

"We faced an enemy who had truly occupied this area and it wasn't easy to push them out, but we did and now they are reduced to almost nothing."