First round

21 candidates registered to run for president^[4][5] of which 19 were approved to contest the election.^[6] Sidi Ould Cheikh Abdallahi, who served as a minister under Moktar Ould Daddah during the 1970s and briefly under Ould Taya in the 1980s, announced his candidacy for president on July 4, 2006.^[7] Ba Mamadou Alassane, President of the Party for Freedom, Equality and Justice (PLEJ), announced his candidacy on July 19, 2006.^[8] The former head of the Central Bank, Zeine Ould Zeidane, announced his candidacy on December 18, 2006.^[9] Dahane Ould Ahmed Mahmoud announced his candidacy on December 23.^[10] Former military ruler Mohamed Khouna Ould Haidalla, who came in second place, behind Taya, in the 2003 presidential election, announced his candidacy on December 27.^[11] On January 2, 2007, Mohamed Ould Maouloud, President of the Union of the Forces of Progress, was designated as his party's candidate.^[12][13] Former coup attempt leader Saleh Ould Hanenna was chosen by his party, the Mauritanian Party for Union and Change (HATEM), as its candidate on January 9.^[14] Ahmed Ould Daddah, the half-brother of Moktar Ould Daddah and the leader of the Rally of Democratic Forces — part of the Coalition of Forces for Democratic Change,^[15] which took a large portion of seats in the November–December 2006 parliamentary election^[16] — announced his candidacy on January 12.^[17] Another former coup attempt leader, Mohamed Ould Cheikhna, announced his candidacy on January 14.^[18] On January 20, Messaoud Ould Boulkheir, President of the People's Progressive Alliance (APP), announced his candidacy.^[19][20] Chbih Ould Cheikh Melainine announced on February 3 that he was withdrawing his candidacy and backing Haidalla, but he was not allowed to officially withdraw his candidacy, although according to Melainine he had requested the withdrawal two days before the February 4 deadline.^[21]

Abdallahi, who ran as an independent, was viewed by some as the candidate representing the ruling junta, and in January he received the backing of an important coalition of 18 parties composed of former supporters of Taya.^[22] Abdallahi denied being the junta's candidate.^[23] The Coalition of Forces for Democratic Change sent a letter to various international organizations, including the African Union, accusing the junta of "running an open campaign in favour of one candidate" through various methods, including asking influential people in the country to back their favored candidate, although the letter did not directly name Abdallahi as this candidate.^[24]

Vall suggested at one point the possibility that, with blank ballots included in the total, no candidate would win a majority of the vote in two rounds, in which case new elections would have to be held. This caused a controversy, and the law was changed so that blank ballots would not count towards the total.^[25]

A record 1.1 million of the population of 3.2 million people registered to vote.^[26] Prior to the election, the frontrunners were considered to be Daddah, Zeidane and Abdallahi.^[27][28]

Second round

After no candidate receiveds a majority of the vote in the first round and Sidi Ould Cheikh Abdallahi and Ahmed Ould Daddah advanced to the second round, on March 14, the Islamist "Réformateurs centristes", which supported Hanenna in the first round, backed Daddah for the second round.^[29] Hanenna also backed Daddah,^[30] as did the candidates Ba Mamadou Alassane,^[31] Mohamed Ould Maouloud,^[32] and Ibrahima Sarr.^[33]

Abdallahi received the support of the third and fourth place candidates from the first round: on March 17, Zeidane announced his support for Abdallahi,^[34] and on March 19, Boulkheir also announced his support.^[35] Boulkheir's support came in spite of the fact that he was part of the Coalition of the Forces for Democratic Change along with Daddah.^[36] Abdallahi also received the support of several minor candidates: Dahane Ould Ahmed Mahmoud, Mohamed Ahmed Ould Babahmed Ould Salihi, Moulaye El Hacen Ould Jiyed, Isselmou Ould Mustapha, and Mohamedou Ould Ghoulam Ould Sidaty.^[30]

A televised debate between Abdallahi and Daddah was held on March 22. It was conducted in a non-confrontational style, with the candidates each explaining their positions.^[37] The candidates advocated similar policies, including measures against slavery, which persists in the country.^[38]

Abdallahi said that it would be easier for him to accomplish things as president because his supporters would constitute a parliamentary majority.^[3] He also said that if he won, he would be willing to include Daddah in the government, as long as his allies agreed.^[39]

First round