A former education minister favored by Paraguay's president held a narrow lead in partial returns for the ruling party's presidential nomination Monday.
If she were to be elected, South America would have three female leaders.
With 92 percent of party primary votes counted, Blanca Ovelar had 45.3 percent of the votes and former Vice President Luis Castiglioni had 44.2 percent. Two other candidates trailed far behind in the quest for the the Colorado Party nomination on the April 2008 presidential ballot.
Party elections chief Oscar Latorre noted that the results were not yet official and said the final, complete count that starts Wednesday probably would not be finished until early January.
President Nicanor Duarte, who backs Ovelar, leaves office in August after a four-year term.
The Colorado Party nomination usually guarantees success: the party has ruled without interruption since 1947.
The nominee is expected to face a left-leaning former Catholic bishop, Fernando Lugo, and a center-right former army general, Lino Cesar Oviedo.
Argentina and Chile already have female presidents.