Lagos (AFP) - Less than two weeks from national polls, Nigeria's ruling party is facing unprecedented shifts in the politics of religion that could spell trouble for the incumbent, President Goodluck Jonathan.
While he may still be the favourite on February 14, experts said two key factors could remove his Peoples Democratic Party (PDP) from power for the first time since the end of military rule in 1999.
First, opposition leader Muhammadu Buhari, a northern Muslim, has gained surprising traction in the mostly Christian south, despite sustained PDP efforts to paint him as a religious extremist.
The PDP could also suffer a historically lopsided defeat in the Muslim-majority north, where the party has previously drawn considerable support, even when a Christian was at the top of the ticket.
- 'Surpassing religion' –
Buhari, a former army general who led a military government for 20 months from December 1983, is hardly the dream candidate for many in the south, experts said.
Some southerners have an entrenched antipathy towards Muslims from the Hausa ethnic group, members of which plundered the country as military rulers through much of the 1980s and 1990s.
PDP efforts to brand Buhari as an extremist devoted to Islamic law have also been successful, said John Campbell, a former US ambassador to Nigeria, now with the Council on Foreign Relations.
"It is grossly unfair. I know him. He is not an extremist but these things resonate," he told AFP.
Buhari, from the All Progressives Congress (APC) party, is making his fourth run at the presidency and has been billed as Nigeria's chief anti-corruption crusader, helping him attract nationwide support.
Analyst Jibrin Ibrahim agreed that for the first time in religiously divided Nigeria, governance could be "surpassing religion" as a campaign issue.
"The issue of religion is very present in all our elections and will be in this one," said Ibrahim, from the Centre for Democracy and Development in Abuja.
"What I think is new about these elections is that it is really about the failures of Jonathan.
"There are voters in the south who don't particularly like Buhari but they have been extremely disappointed with the last four years and that could shift support to Buhari."
Jonathan has been heavily criticised for his apparent failure to reduce graft in Africa's most populous country and top economy, where billions of dollars in public money have been stolen, especially in the oil sector.
Boko Haram's brutal uprising has also worsened each year under Jonathan's watch, with more than 13,000 people killed since 2009.
- Rotation in 'disarray' -
The PDP has won all four presidential elections since 1999 with support from both the north and the south, which it secured through an unwritten power-sharing agreement within the party.
Power brokers in both regions "were comfortable using the PDP as a venue through which they would arrive at a rough consensus" because it was understood that each side would get its turn in charge, Campbell said.
The 2010 death in office of Jonathan's predecessor, Hausa-Muslim Umaru Musa Yar'Adua "put that agreement in disarray", analyst Idiyat Hassan wrote on the African Arguments blog.
Jonathan's rise from the vice-presidency and his refusal to stand aside for a northerner in 2011 caused initial cracks in the PDP's national alliance.
His insistence on running for a second term in 2015 split the party, with the north emerging as "the great losers" of the once dominant PDP coalition, Campbell said.
Several key northern politicians have quit the PDP and joined the APC over the last two years, including Rabiu Kwankwaso, governor of the north's most populous state, Kano, which has five million registered voters.
Jonathan beat Buhari by roughly 10 million votes in 2011, winning roughly eight million in the north and the religiously divided central states.
If Jonathan's support in the north collapses and Buhari makes inroads in the south, analysts said the president could lose.
Buhari is helped by the fact that he is leading a united opposition, unlike in 2011 when rival candidates peeled off more than three million votes.
- Looking past religion -
Some argue that parties spend too much effort striving for ethno-religious balance, noting that the most popular presidential ticket since independence in 1960 -- the 1993 campaign of the Social Democratic Party -- contained two Muslims.
Moshood Abiola and running mate Baba Gana Kingibe were easily on track to win the polls before military ruler Ibrahim Babangida nullified the vote.
Many commentators were clamouring for popular Lagos state governor Babatunde Fashola, a Muslim, to head the APC ticket in 2015, but the party decided it needed a Hausa candidate to defeat Jonathan.
For Dapo Thomas, political scientist at Lagos State University, the emphasis on a candidate's religion and tribe has "driven merit to the backseat".