He has predicted that he will win with a crushing majority, but the scene inside the polling station where he has voted for decades shocked even longtime observers of this country. Wade was jeered and insulted when he arrived to vote.
The protests that began after the court's ruling are uncharacteristic for Senegal. Six people have been killed in the violence. The opposition has vowed to render the country ungovernable should he win.
Voting throughout the capital got off to an orderly start, and turnout appeared high, said Thijs Berman, head of the European Union observation mission. The main exception was the province of Casamance, where a low-level rebellion has simmered for years.
In a volatile part of the world, Senegal has long been seen as the exception.
Mauritania, to the north, held its first democratic election in 2007, only to see the president overthrown in a coup a year later. To the south, Guinea-Bissau's president was assassinated two years ago. And farther south in Ivory Coast, mass graves are still being unearthed containing the victims of last year's postelection violence.
"For many years we all wrote and spoke about Senegal as being different," said Africa expert Chris Fomunyoh at the National Democratic Institute for International Affairs in Washington. "Senegal has been viewed as the anchor in the subregion. And today, the metal on that anchor is melting before our very eyes."
Wade was once hailed as a hope for Africa. He spent 25 years as the opposition leader of this nation of more than 12 million, fighting the excesses of the socialist regime that ruled Senegal from 1960 until 2000 when he was first elected.
Unrest is being fueled by a sense that the country's institutions are being violated, starting with the constitution. And half of the people in Senegal still live below the poverty line, according to the World Bank.