Wade, 85, is trying to extend his rule despite a 2001 reform limiting presidents to two terms. The Constitutional Court, appointed by the president, ruled last month the reform does not apply to Wade because he was already in office when the rule was changed, Voice of America reported.
Wade was booed by the crowd Sunday as he voted in his home district. The Financial Times said the president is unlikely to get 50 percent majority needed to win the election and will likely face a runoff in mid-March.
Former Nigerian President Olusegun Obasanjo has been trying to mediate the crisis and has proposed a two-year office for Wade, which has done little to appease angry protesters, This Day, Lagos, Nigeria, said.
At least six people have died in anti-government protests.