Radev of the Bulgarian Socialist Party is winning 58% of the vote, whereas his rival, Tsetska Tsacheva of the ruling Bulgarian Citizend for European Development party is scoring 36%.
The voter turnout at the runoff presidential elections on Sunday was 48%.
"We expected this victory. But we will be rejoicing for about 24 hours and then it will be time to work. What has happened today in Bulgaria needs serious work," Stefan Danailov, the chairman of the committee which nominated Radev as candidate, said in an interview with bTV.
The second round of presidential election was held in Bulgaria on Sunday. More than 12,000 polling stations were organized in the country, where about 6.8 million people are eligible to take part in the presidential elections.
Additional 325 polling stations were opened for Bulgarian citizens in 71 countries.
More than 2,000 observers monitored the polling, including 45 international observers.
Opposition candidate Rumen Radev winning presidential elections in Bulgaria
14 November 2016
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Opposition candidate Rumen Radev is winning runoff presidential elections in Bulgaria, according to exit poll results.
