Central American politics could see a historic surge to the left in elections on Sunday.
Among the favourites in Costa Rica is environmentalist José Maria Villalta of the Broad Front Party.
He will go up against former San José Mayor Johnny Araya from the governing National Liberation Party.
But the election outcome is far from certain, with one right-wing candidate – Otto Guevara – and one from the centre-left – Luis Guillermo Solis – following close behind in the polls.
El Salvador will also vote on Sunday, in another Central American presidential election that is too close to call.
Vice President Salvador Sanchez Cerén of the governing left-wing FMLN leads the polls.
Former San Salvador mayor Norman Quijano of the rightist Nationalist Republican Alliance (ARENA) is currently in second.
Candidates need to gain a minimum of 50 percent of the vote in El Salvador and 40 percent in Costa Rica to win outright and avoid a second round of votes.