Incumbent President Georgi Parvanov, backed in the last election by his Socialist Party and other leftist organizations, is expected to run for a second five-year term.
During Parvanov's presidency, the Balkan country has joined NATO and finished preparations for membership in the European Union, which it hopes to join next year, the AP reports.
Despite his widespread popularity, the 49-year-od historian is expected to face a strong challenge from right-wing parties, if they succeed in rallying behind a joint candidate.
In Bulgaria, most power rests with the prime minister and parliament. The president has little influence over the country's economic and foreign policy. Still, the presidency carries moral authority and legislative veto power.