Senegal will hold a first round of presidential elections on 26 February.
Incumbent President Abdoulaye Wade, known as "the hare", is among the 14 candidates, including two women, who are standing for election.
Opposition and civil society activists claim Mr Wade's bid for a third term is illegal because the constitution imposes a two-term limit for presidents.
But the Constitutional Council said the 85-year-old president was not bound by a two-term limit because his first term began before the rule was introduced.
Over the past few months his candidacy has triggered a number of protests and deaths which could endanger his country's record for democracy and stability.
But the opposition has failed to united behind a single candidate. Here are brief profiles of the main contenders vying to unseat Mr Wade.
Ousmane Tanor Dieng: Socialist Party
The 65 year old was the campaign manager for Senegal's former President Abdou Diouf when he lost the Socialist Party's 40-year grip on power in 2000.
Popularly known as "Tanor", he has a law degree.
Mr Dieng had agreed to run as part of the opposition coalition Bennoo Siggil Senegal (United to Boost Senegal) - but when Moustapha Niasse was chosen as its candidate, he decided to stick with his old party.
He ran against Mr Wade in 2007, winning 13.5% of the vote.
Born in 1939, Niasse has a long political CV and is no stranger to presidential elections, having run twice before.
He was private secretary to Senegal's first President Leopold Sedar Senghor, and prime minister and foreign minister to his successor Mr Diouf.
He served several stints as foreign minister for the Socialist Party and has been involved in mediating crises in Africa.
In 1999 he created his own party, the Alliance of Forces for Progress, and was briefly aligned with Mr Wade - serving as his prime minister before the two fell out after a year.
In 2007 he came fourth with 6% of votes.
Outside politics, he served as the special representative in the Great Lakes of the UN secretary general and he comes from the family of one of Senegal's powerful religious brotherhoods.
The 50-year-old geologist is the mayor of the western city of Fatick.
He is taking part in elections for the first time after falling out of favour with his former mentor Mr Wade, whom he had served as a special adviser.
He was also mining minister and interior minister and, between 2004 and 2007, prime minister.
He was then elected as head of the national assembly but resigned in 2008 - after he summoned the president's son, Karim Wade, to be questioned by MPs.
Mr Sall has promised to decentralise government and and improve the management of public funds.
Popularly known as "Idy", the charismatic Mr Seck, 52, was once seen as being groomed by Mr Wade as a successor.
He came to the fore in the post-Senghor era, serving under Mr Diouf and as prime minister in the early days of the Wade government - again until the two parted ways.
He spent 199 days in jail on breach of state security and corruption charges - but there was no trial.
Born in 1959, he was a minister in a unity government under Mr Diouf and then chief of staff and prime minister under Mr Wade until 2005.
He is the leader of the Rewmi party (the country) and the mayor of Thies, Senegal's second city.
He finished second in the 2007 presidential election, behind Mr Wade.
Mr Seck has a background in finance and business development, and has promised to privatise the energy sector - Senegal experiences frequent, severe power cuts.