Cameroon will go to the polls this weekend as opposition parties mount an eleventh-hour unity bid to dislodge six-term President Paul Biya while the country faces unprecedented insecurity.Two leading opponents of the 85-year-old incumbent have combined forces while talks among the remaining field of seven opposition candidates about a "super coalition", as happened in 1992, were understood to be ongoing on Saturday.Cameroon's 6.5 million eligible voters will cast their ballots on Sunday to a backdrop of ongoing violence and tensions in the country's English-speaking southwest and northwest, which have been rocked by an anglophone insurgency launched a year ago in the mainly francophone country.The violence has claimed the lives of at least 420 civilians, 175 members of the security forces and an unknown number of separatists, according to the International Crisis Group (ICG) think-tank.In Kumba, a village in the southwest, one civilian, one police officer and one suspected separatist were killed in the last week alone.The far north region also continues to be mired in insecurity, as fighters of the Nigeria-based Boko Haram group mount cross-border raids and attacks despite a military surge to drive out the jihadists. 'Not preparing for war' In a rare coordinated political manoeuvre, one of the key opposition frontrunners, Maurice Kamto, agreed late Friday to a unity deal between his Movement for the Rebirth of Cameroon's (MRC) and the People's Development Front (FDP), meaning he will stand on behalf of both parties.The FDP leader Akere Muna has called on his supporters to back Kamto, in the first such tactical pre-election tie-up since John Fru Ndi stood as the sole opposition candidate in 1992 in polls that his supporters say he won, but were manipulated to hand victory to Biya.But it is unclear whether the eleventh hour deal was done in time to affect the vote, which runs from 0700 GMT until 1700 GMT Sunday."This alliance, though interesting for the vitality of Cameroonian democracy, may have arrived too late," said Hans de Marie Heungoup, an ICG researcher. Kamto's MRC has warned that a "massive fraud" was underway to secure a Biya win in the vote."We're not preparing for war, but wherever there is fraud, there will be a firm response," said MRC spokesperson Paul-Eric Kingue.But the government hit back, apparently in response to the MRC, saying that it would "not tolerate any disorder before, during or after the presidential vote". Communication Minister Issa Tchiroma Bakary said in a statement that "measures have been taken... to prevent any actions that might create violence or disorder around the elections".He added that "political figures linked to foreign interests were preparing groups of agitators to stir-up violence in the event that the results don't go their way". Election uncertainty It is unclear if polling will proceed normally across Cameroon's English-speaking region where separatists hold a "significant" amount of territory, according to the ICG, and have threatened to disrupt the vote."I tell people: after the election, things will be OK," said John Ngomba, a tour guide in the town of Buea, the capital of the southwest region which has been at the heart of the fighting and is rocked by near daily clashes.A burnt-out lorry and car, allegedly targets of a recent separatist arson attack, sit in a ditch opposite a market, with charred, twisted metal spilling onto Buea's main road, a testament to the ongoing conflict.A total of 246 000 people have fled their homes in the southwest and 25 000 have left the country altogether for Nigeria, according to UN figures.It is thought that the displaced will struggle to cast ballots which could favour Biya as anglophones have traditionally backed the Social Democratic Front (SDF) party, whose candidate Joshua Osih could suffer at the ballot box.In the capital Yaounde however, residents were more concerned about the unpredictable weather."I'll vote tomorrow, it's my duty as a citizen and I do it with pride. I'll be voting for my candidate Paul Biya. He's the president of all Cameroonians," said Yaounde resident Ebanda Ebanda Beckey Thomas who wore a blue and white "Biya" scarf."His determination to help Cameroon develop pleases us, the things that he's done for our country in the areas of education and health too," he added as he dodged the rain. Despite the ubiquity of Biya's posters across Cameroon, he has been virtually invisible during the campaign."The force of experience," proclaim giant billboards in all of Cameroon's large urban areas.Biya made a brief public appearance in the electorally-crucial far north region last weekend but otherwise has not been seen or heard. Results must be posted within 15 calendar days of the poll by law, and authorities have previously waited the full fortnight before announcing the winner.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.