Bulgarians began voting Sunday in an election run-off for the country's president, a post that carries little real authority, but could determine the fate of Prime Minister Boyko Borisov, dpa reported. The often unreliable Bulgarian opinion polls predict a clear win for Rumen Radev, formally without party affiliation but endorsed by the opposition Socialists. Conservative Prime Minister Borisov has however promised to resign if Tsetska Tsacheva, the nominee of his GERB party, loses. The winner is scheduled to replace Plevneliev on January 22. He had declined to seek a second 5-year term.