Natalia Díaz Quintana and Otto Guevara Guth concluded with a message of party unity on Sunday’s election day.
One of them will be elected as the presidential candidate of the Libertarian Movement for the 2018 elections.
The closed convention in which both lawmakers participated, is the first in the history of the party that debuted in a national election in 1998.
Díaz, 32, faced veteran Guevara, 57, who opts for the fifth time for the party’s candidacy.
The 81 polling stations were scheduled to close at 4 p.m.
Unlike the National Liberation, Christian Social Unity and Citizen Action parties, the Libertarian Movement held a closed convention in which only members previously registered in the group were entitled to vote.