Exit polls in Bulgaria indicated Sunday that opposition candidate Rumen Radev has won the presidential election runoff, defeating conservative Prime Minister Boyko Borisov's candidate Tsetska Tsacheva, according to dpa. Borisov has repeatedly promised to resign if his preferred candidate loses. On election day, he said he and his GERB party "will not remain in power another day if we lose." Projections gave Radev, a reserve army general without formal party affiliation who was backed by the Socialists, 58 per cent of the votes. Tsacheva was projected to win 32 per cent. Final official results are not expected on Sunday. Radev, 53, is seen as leaning towards Bulgaria's closer ties with Russia. Tsacheva sought to become the country's first woman president and stick with incumbent Rosen Plevneliev's pro-Western position. Last week, however, Radev dismissed media speculation that he opposed Bulgaria's membership in NATO. After the exit polls were released, he declared the outcome as a "victory for all Bulgarians," accusing the rival camp of sowing anxiety that he wanted to pull Bulgaria out of NATO and praising the voters for "overcoming fear." In any case, the office of the president carries limited authority, with most of the power concentrated in the hands of prime minister. It was not immediately known when Borisov planned to make good on his promise. He has, however, made it clear that he would not seek another coalition. Borisov faces declining popularity amid Bulgarians' discontent with being the poorest nation in the European Union as well as their frustration with political and judicial corruption. Even without Tsacheva losing, Borisov's three-way governing coalition - which is increasingly fragile - would have been liable to crumble before the scheduled parliamentary election in 2018. It was also unclear whether the Socialists would attempt to form a new majority or opt for snap polls two years early, to possibly capitalize on Borisov's poor standing in opinion surveys. The winner is scheduled to replace Plevneliev on January 22. He had declined to seek a second 5-year term.