QUITO - Some 12.8 million eligible voters will go to the polls on Sunday to choose a successor to President Rafael Correa, whose 10-year tenure brought much-needed stability to the South American nation.

From 1997 to 2007, Ecuador had seven presidents, the last three were ousted before the end of their four-year term.

The current election is being closely watched to see whether the ruling PAIS Alliance will be given another four-year mandate to continue the "Citizen Revolution" it set in motion, or whether Ecuadorians will vote for a return to neo-liberalism, the only other political current on offer now in Latin America.

The two leading candidates are Lenin Moreno, of the progressive PAIS party, and ex-banker Guillermo Lasso, of the center-right Creating Opportunities (Creo) party.

"Two economic models are at stake: the politically progressive project the government has developed over the past 10 years and the old business model, which had severe consequences on the life of the nation," political analyst Juan Paz y Mino told Xinhua in an interview.

Polls show Moreno holds a commanding lead, but not enough to win an outright majority of more than 50 percent, or 40 percent with a 10-percent difference over his closest rival, as required by Ecuadorian law.

That means an April runoff is likely, and that would give Lasso a real shot at the presidency, if the other eight opposition political parties or coalitions unite behind a single candidate.

"Today in Ecuador there are two certainties and one doubt. The first certainty is that there is going to be a runoff; the second is that we are going to be in the runoff. And the doubt is, in what order are we going to come out, quite likely, we are going to come out first," A fairly confident Lasso told the press.

Though Ecuadorians appear to be generally satisfied with the current government, a corruption scandal at state-run oil company Petroecuador has tarnished the image of incumbent vice president Jorge Glas, who is also Moreno's running mate.