Senegal's President Macky Sall has postponed this month's elections following complaints after dozens of candidates were barred from standing.
The two-term president, who reiterated that he would not be seeking re-election, did not set a new date.
Amid controversy, a constitutional council had prevented several hopefuls - including some high-profile politicians - from running.
Mr Sall said "these troubled conditions could gravely hurt" the ballot.
He added that he would start "an open national dialogue... to create the conditions for a free, transparent and inclusive election in a peaceful and reconciled Senegal".
An opposition candidate called the president's decision to postpone the election a constitutional coup.
Khalifa Sall, former mayor of the capital, Dakar, urged people to protest against the move and his political coalition has pledged to go to court.
An organisation of influential Islamic clerics had warned against postponing the vote, saying it risked destabilising the nation.
The move to delay the election is unprecedented in a country that is seen as one of the most stable democracies in the West African region.
In a statement, the Economic Community of West African States (Ecowas) expressed its concern over the situation.
It also urged "the competent authorities to expedite the various processes," in order to set a new date for the elections.
Twenty candidates had made the final list, but among the most prominent of those who had been excluded from the original vote, scheduled for 25 February, was opposition politician Ousmane Sonko.
The popular figure was barred because of a libel conviction. Sonko, who has faced a number of court cases, said he had been the victim of a campaign to stop him standing for president.
Karim Wade, the son of a former president, was also prevented from taking part because he is allegedly a French citizen as well as being Senegalese. He has described the accusation as "scandalous", the AFP news agency reports.
Mr Wade's backers in parliament questioned the neutrality of two of the judges on the panel that decided on the final list of candidates.
Some politicians have argued that the rules for candidacy were not applied fairly. Something the authorities have denied.
BBC