After weeks of riots, Senegalese voters began casting their ballots Sunday in an election that threatens the country's image as one of the oldest and most robust democracies in Africa.

This normally unflappable nation on the continent's western coast has been rocked by back-to-back protests following the decision of its 85-year-old leader to seek a third term. The opposition has vowed to render the country ungovernable if President Abdoulaye Wade wins Sunday's poll.

By running for re-election, Wade is violating the term limits he himself introduced into the constitution. The deadly riots began last month, when the country's highest court ruled that these restrictions should not apply to Wade since he was elected under an earlier constitution that didn't include term limits.

Moussa Signate, a security guard, sat against the cement wall of an elementary school that had been transformed into a polling station on a downtown boulevard, watching others line up to vote. Lines snaked outside the doors of the classrooms, but Signate said he was so discouraged that he was considering not voting at all.

"I am thinking about the future of my country," said the 47-year-old. "People have had enough. If you earn, like me, 80,000 francs ($160) a month, and a bag of rice costs 25,000 ($50), how are you supposed to live? We are a peaceful people, but you can't push us and expect nothing. If Wade wins, it will be chaos."

First elected 12 years ago, Wade was once hailed as a bright hope for Africa. He spent 25 years as the opposition leader of this nation of 12 million, fighting the excesses of the former socialist regime that ruled Senegal from 1960 until 2000 when Wade was finally elected.

Many of the people lining up to vote had initially supported Wade in the 2000 election. The landmark vote marked one of the first peaceful transfers of power from one party to another in the region, which is better known for coups and strongman rule.

And many said they voted for him a second time in 2007. It's when he decided to run for a third, seven-year term that voters here said they lost faith, both because of the perceived violation of the constitution and because of his advanced age. If Wade wins the poll, he will be in office past his 92nd birthday in a nation where the average person doesn't live past 59.

The anger is combined with the fact that one in two people in Senegal still live below the poverty line, according to the World Bank.

For days before the vote, Olusegun Obasanjo, the former president of Nigeria who has made a career as a mediator of African conflicts, shuttled between the presidential palace and the 13 opposition candidates in an effort to find a solution.

Late Saturday, Obasanjo proposed a roadmap that was accepted by neither side, and which would have called for Wade to step down after two years, instead of after seven, if he were to win Sunday's election.

"We believe this country is so beautiful, so great, so important to the people of this country, to our sub-region of West Africa, to Africa — and indeed to the world. And nothing should be done to undermine its greatness and its beauty," Obasanjo said. "We believe it is in the interest of this nation that unity should be maintained."

Senegal is unlike any other country in the region, and its immediate neighbors are a sobering reminder of what could lie in store if the election sparks further conflict. To the south in Ivory Coast, people are still unearthing mass graves from the postelectoral conflict that engulfed that nation following the 2010 election.

Unlike its neighbors which began experimenting with democracy in the 1960s after independence, Senegal has been holding regular elections since the mid-1800s, when the citizens of this former French colony were given the right to elect a deputy to the French parliament.