Bulgarians are voting in a presidential election on Sunday, as security concerns swirl following a series of drone attacks on ships in the Black Sea.
President Iliana Iotova, who favours dialogue with Moscow and opposes military aid to Ukraine, is the frontrunner for a new term in the largely ceremonial post, polls show.
Iotova, 62, is expected to win between 41 and 47 percent of the vote, according to surveys.
Her main challenger Andrey Gyurov, a banker and former caretaker prime minister backed by the pro-Western opposition, is polling at 28-31 percent.
The leader of the pro-Russian far-right Vazrazhdane party, Kostadin Kostadinov, is in third place on 10-13 percent.
Polling stations opened at 7:00 am local time (0500 GMT) and close at 8:00 pm.
Iotova took over this year as president of Bulgaria, a European Union and NATO member state, when Rumen Radev stepped down to run in parliamentary elections, eventually becoming prime minister.
If successful in a runoff set for November 1, she would become the first woman ever elected president in the country of 6.4 million people.
A win for Iotova would be a boost for Radev, who has also called for dialogue with Moscow.
A former journalist and member of the European Parliament, Iotova was elected vice-president alongside Radev in 2016 and 2021.
'President of peace'
Appealing to patriotic sentiment, she launched her campaign by the Golden Church in Veliki Preslav, the former capital of the First Bulgarian Empire.
Calling for national unity and action against poverty in the EU's poorest member state, she has also made peace in Ukraine a central theme of her campaign, promising to be a "president of peace".
Without questioning Bulgaria's membership of the EU or NATO, she opposes military aid to Ukraine and advocates negotiations.
"We do not need a Coalition of the Willing for Ukraine, but a Coalition for Peace in Ukraine," she said at a rally in Varna, arguing that military support would prolong Russia's invasion.
At another rally for Iotova in the southern town of Dimitrovgrad, retired teacher Irina Ilieva, 85, said the Ukraine war was her main concern.
"Whoever is elected... will have to do everything possible to ensure that the problems are resolved peacefully," she said.
Four vessels were struck off Bulgaria's coast this month, leaving 21 people missing, in suspected spillover from the Russia-Ukraine war.
While Radev said the attacks appeared to serve Russian interests and summoned the Russian ambassador, his government insists there is so far no evidence directly linking Moscow to them.
An American P-8 Poseidon reconnaissance plane has started to patrol the Black Sea following Sofia's call for help after the attacks.
