According to Alpha Research agency, the Bulgarian Socialist Party-backed Major General Rumen Radev is expected to have 24.8 percent of the valid votes, against 23.5 percent for the GERB party candidate Tsetska Tsacheva.
Another exit poll conducted by Gallup International showed that 26.7 percent of voters cast their ballots for Radev, and 22.5 percent voted in favor of Tsacheva.
The two exit polls showed that the nationalist candidate Krasimir Karakachanov came third with 13.6 percent and 15.0 percent of the votes respectively.
A candidate has to receive more than 50 percent of the votes to be elected in the first round.
Therefore, Tsacheva and Radev will compete in a runoff a week later.
The official results are expected to be released on Tuesday.
As many as 21 candidates participated in the presidential elections.
Incumbent President Rosen Plevneliev, who won the last presidential elections in Bulgaria in October 2011 as a candidate of the GERB party, has decided not to run for a second five-year term “for personal reasons.” Endit