Rumen Radev, a former Bulgarian president and ex-fighter pilot, is leading in the polls with his Progressive Bulgaria coalition at around 30 percent, ahead of former Prime Minister Boyko Borisov's centre-right GERB party on roughly 20 percent.
Radev has built his campaign on promises to fight corruption and restore political stability, but his past statements on Russia and Ukraine have drawn attention in Brussels.
He previously described Russian-occupied Crimea as "currently Russian", opposed sanctions on Moscow before Russia's full-scale invasion in 2022, and in 2023 accused the Ukrainian government of wanting "to continue the war that Europeans are paying for".
When Bulgaria's caretaker government signed a ten-year cooperation agreement with Ukraine in late March, Radev accused it of "dragging us into war".
US news outlet Politico notes that the EU lost Viktor Orbán from its group of "disruptors" following the Hungarian elections, but may gain a new member in Radev after Sunday's vote.
His coalition has also attracted support from pro-Russian and far-right voters, according to polling.
Bulgaria is one of Ukraine's key suppliers of Soviet-era ammunition, including artillery shells, rocket launcher rounds and components for air defence systems.
An anonymous EU official told Politico the Bulgarian election result "could be of crucial importance for the EU’s ability to support Ukraine and counter Russia".
The shape of any future coalition remains uncertain.
Bulgarian analyst Dimitar Bechev told Politico that Radev could align either with the reformist bloc or with the right – and that this is the biggest unanswered question ahead of Sunday's parliamentary elections.
(ał)
Source: PAP, Politico