A look at the candidates in the run-off for Bulgaria's presidency:
Supported by the ruling center-right GERB party of Prime Minister Boiko Borisov, Plevneliev, 47, is an engineer and former entrepreneur. As minister for regional development in the current government, he has been lauded for pushing through several large-scale infrastructure projects. Plevneliev pledges to support the government's drive to reform Bulgaria, which is plagued by corruption and economic crisis. He is seen as calm and pragmatic, but there are concerns that he will be overshadowed by the influential prime minister.
The candidate of the opposition Socialist party, Ivailo Kalfin, 47, is a former foreign minister and a current member of the European Parliament. Kalfin is one of the few leading left-wing politicians seen as largely untainted by the Socialist party's communist past. He built his campaign on warnings that a victory by his opponent risks giving one party a monopoly over all state institutions. Kalfin has promised to safeguard democracy and support the rule of law.