According to three polling stations, Yotova, who advocates dialogue with Russia and opposes military support for Ukraine, will receive 35–36.5 percent of the vote on Sunday.
The challenger, the more pro-Western Andrei Gjurov, who wants to see an increased NATO presence in the Black Sea, is polling at 32.2 to 32.5 percent.
A 50 percent majority is required to win in the first round. Yotova and Gjurov look set to meet in a decisive second round next Sunday.
The presidential election is primarily about economic hardship and the war in Ukraine.
A series of drone attacks on ships in the Black Sea have fueled debate about the war and the security situation ahead of the largely ceremonial Bulgarian presidential election.
Yotova is backed by Prime Minister Rumen Radev, who in June decided to stop arms deliveries to Ukraine from his army's own warehouses.
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