Africa's top envoy has proposed Senegal's President Abdoulaye Wade retire in two years if he is re-elected, in a bid to stamp out tensions on the eve of the nation's most contentious polls yet.
The west African nation, a haven of stability on the continent, is anxiously awaiting the start of the vote where the 85-year-old Wade is seeking a controversial third term.
Wade's candidacy, which came after he circumvented term limits that he previously introduced into the constitution, sparked weeks of protests that left six people dead.
Speaking in Zambia, UN Secretary General Ban Ki-moon said he was "concerned" by the pre-poll violence and urged "peaceful and transparent" elections.
Nigeria's ex-president Olusegun Obasanjo "introduced a new element, a roadmap which states Abdoulaye Wade will only stay in power for two years if he wins," said Abdoul Aziz Diop, spokesman for the opposition June 23 Movement (M23).
"Our wish remains that Abdoulaye Wade loses the election," he said, noting that Wade has not promised to resign after two years.
"It is these guarantees which will carry the coming negotiations with Obasanjo."
Obasanjo's deal also calls for creating a new constitutional court and independent electoral commission, M23 co-ordinator Alioune Tine told RFM radio, saying the opposition movement was "open to negotiations...to conserve peace."
Obasanjo arrived in Dakar on Tuesday as head of a joint mission launched by the African Union (AU) and the Economic Community of West African States (ECOWAS) and has met with Wade, the opposition and diplomats.
His arrival came after days of riots over Wade's candidacy that turned parts of Dakar into a no-go zone as police fired teargas at rock-throwing protesters who had set up flaming barricades.
With polls set to open, the rapper-led youth movement "Fed Up" urged voters against boycotting, encouraging them to get their voter cards and vote massively against the incumbent.
"The struggle must continue and will continue at the ballot box. We have been sharpening our weapons, your voters cards. The time has come to use them," the movement said in a statement late Friday.
Wade has already served two terms in office, but argues the changes to the constitution in 2008 extending term lengths to seven years allow him to serve two more mandates.
The country's top legal body validated his candidacy on January 27, sparking riots around the country and clashes in downtown Dakar.
Observers say Wade needs to secure a first-round victory because he would fare badly in the second-round when the field contracts to two candidates.
Thirteen opposition candidates are on the first round ballot, including three former prime ministers, but no clear front-runner has emerged.
Foreign partners have voiced concern over the unsettled campaign -- uncharacteristic for Senegal, which boasts an unbroken series of elections since independence in 1960 and has never suffered a coup.
The United States has sent its top Africa diplomat Johnnie Carson to Senegal to underline its "desire to see calm, free, fair elections," the State Department said Friday.
Some worry that more than 450,000 unclaimed voter cards boost the prospect of fraud, but the elections body insists it is ready to manage the polls.
Roughly 5.3 million people are registered to vote.
Paul Melly, an analyst with London-based Chatham House, told AFP that a Wade first-round win could "could produce a further upsurge in protest and anger on the streets."
Wade was first elected in 2000 to great euphoria after unseating the Socialist Party that had been in power for 40 years.
His supporters praise him for an infrastructure boom, but his detractors say he has focused on prestige projects while the average Senegalese battles rising food prices and crippling power cuts.
Infuriating the opposition are signs he is lining up his son Karim Wade to succeed him.