Sunday's run-off poll between Sidi Mohamed OuldCheikh Abdallahi and Ahmed Ould Daddah comes after no candidate managed tosecure 50 per cent of the votes in a first round two weeks ago.
The ballot marks the final stage in
Both candidates spent time in prison during thecountry's military rule.
About 1.1 million people are eligible to vote inSunday's election.
Both candidates have promised reforms and aconsolidation of democracy in the country whose largely nomadic populationis a complex mix of Arabs and Africans and where slavery persists.
Abdallahi is supported by a powerful coalition of 18 political groups onceloyal to Maaouiya Ould Taya, who seized power in 1984 and ruled for 20 years.
Daddah, an ardent critic of Taya, was minister of finance when his half brotherMoktar Ould Daddah, the country's first post-independence leader, was inoffice.
Abdallahi won 25 per cent of the vote in the first round of the election,while Daddah finished with 21 per cent.
On Friday, Abdallahi said because his coalition has a majority in parliament,he would be able to accomplish things more quickly.
"We can move the country forward with the largest coalition possible," he said, presenting himself as the consensuscandidate.
Daddah spoke about not returning to the past, denouncing "groups wholooted the country for 20 years and want to continue to do it".
"But a new hope is born," he added.
Both candidates have said they will review the country's diplomatic ties with
But the new president's greatest challenge will be totackle poverty and widespread social and economic imbalances.
Güncelleme Tarihi: 20 Eylül 2018, 18:16