Bulgarians are voting in a snap election, following the resignation of a Socialist-led government in July, the BBC reports.
Opinion polls suggest the centre-right GERB party may win most of the votes but fall short of an overall majority in the 240-seat parliament.
Its main rivals are the Socialists (BSP) and the ethnic-Turkish DPS party.
Bulgaria – the poorest country in the European Union – has been rocked by recent protests over low living standards and by a banking crisis.
GERB, led by former PM Boiko Borisov is predicted to win the polls, but is likely to rely on smaller parties to be able to form a governing coalition.
“Right now I don’t see how and with whom to form a government,” Mr Borisov was quoted as saying by the AFP news agency earlier this week.
The splits in the Socialist-led government of now ex-PM Plamen Oresharski began to appear after the party’s disastrous showing in the European Parliament elections in May.
However, the rift with DPS, the former junior partner in the coalition, was seen as the main reason for the cabinet’s resignation.
A controversy around the South Stream pipeline, meant to carry Russian gas to Western Europe via Bulgaria, also played a big part in the government’s downfall.
Mr Oresharski was criticised for moving ahead with construction of the pipeline, a project frowned upon by Brussels for breaching EU rules.
In June, shortly after the announcement that Bulgaria had stopped work on the project, the country witnessed a run on two of the country’s largest banks that also heightened political uncertainty.
One of them, the Corporate Commercial Bank (CCB), was closed after panicked customers withdrew millions on their deposits.