Bulgarians are heading to the polls for the third time in four years in a snap vote that could tilt the European Union's poorest member country closer to Russia.
Polls on Sunday opened at 7 a.m. (0400GMT) and first results from exit polls are expected shortly after they close at 8 p.m. (1700GMT).
Some 6.8 million Bulgarians are eligible to vote in an election widely predicted to bring about a fragile government coalition and a fragmented legislature where nationalist and populist parties could become kingmakers.
Surveys say former Prime Minister Boiko Borisov's center-right GERB party is running neck-and neck with the Socialist Party of ex-communists. Both parties have pledged to improve economic relations with Russia, appealing to voters who feel let down by the EU.
The election has sparked protests at the Turkish border for the last two days by Bulgarian far-right groups who are determined to keep Bulgarian citizens living permanently in Turkey from coming in to vote.
The border blockade reflects rising tensions between the two countries over Turkey's open backing for a group that represents Bulgaria's sizeable Turkish minority. Some 10 percent of the 7.2 million Bulgarians are of Turkish origin or are Muslims. More than 300,000 have settled permanently in neighboring Turkey, but still hold a Bulgarian passport and are eligible to vote in Bulgaria.
The blockade by nationalists could affect some 50,000 voters from Turkey.
In spite of the threat of the far-right and limitations by the Bulgarian government, Turkish-Bulgarians will vote in the elections. The political parties "Movement for Rights and Freedoms," and "Democrats for Responsibility, Freedom and Tolerance," which were established by Turkish minorities in Bulgaria, will also participate in the general elections, a fact that has disturbed some ethnic Bulgarian political parties afraid of losing voters. There are 588,318 Bulgarians of Turkish descent in the country, making them the country's largest ethnic minority with 8.8 percent of the population.
The protesters claim that Turkish officials are encouraging expatriate voters to support DOST, a pro-Ankara party that is running in the election for the first time.
President Recep Tayyip Erdoğan has criticized what he described as pressure on ethnic Turks in Bulgaria ahead of the election