Bulgarians are voting for a new president in a runoff election that pits a Russia-friendly Socialist candidate against the country's parliament speaker.
Rumen Radev, a former air force commander and newcomer to politics, has campaigned on an antimigrant, pro-Moscow message.
Opinion polls have shown Radev consistently ahead of Tsetska Tsacheva (eds: a female), who is backed by the right-of-center GERB party.
Voting booths opened at 7 a.m. (Prague time) on November 13 for the country's 6.8 million registered voters. First results are expected later in the day.
"Until recently I flew a Soviet jet fighter. I have graduated from a U.S. academy. But I am a Bulgarian general. My cause is Bulgaria," said Radev, 53.
But Radev has called for an end to EU sanctions against Russia and said Sofia should be "pragmatic" about its stance regarding Moscow's annexation of Ukraine's Crimean Peninsula.
Backed by the opposition Socialists, Radev narrowly beat Tsacheva in the November 6 first-round election, 25.5 percent to 22 percent.
Corruption and a dismal economy under the center-right government of Prime Minister Boiko Borisov has worked in Radev's favor.
The Bulgarian president's post is a largely ceremonial position.
Based on reporting by Reuters and TASS