Rumen Radev

The GERB candidiate who came second in Sunday's first round of Bulgaria's presidential election issued a stark warning on Monday about the future of democracy if her left-wing rival wins the second round run-off on November 13.

It is worth remembering that "socialists were already Presidents of Bulgaria" but it remained a "docile" NATO member and implemented EU directives unperturbed, a Russian daily says.

The opinion piece is a comment on the win of socialist-backed candidate Rumen Radev in the first round of Bulgaria's presidential election and the prospect of him winning the runoff vote.

Bulgarian Prime Minister Boyko Borissov said his GERB party will quit the government if his party's candidate in the presidential election loses the second round on November 13.

The Bulgarian national interest will be the core priority of the newly emerged nationalist coalition even after the presidential election, candidate Krasimir Karakachanov has said.

Bulgarians said no to apathy and voted for change, Rumen Radev, the main opposition party's presidential candidate has said.

Radev has earned the best result in the vote held on Sunday, with the ruling GERB party's candidate Tsetska Tsacheva lagging behind.

Polling stations will be open till 8pm on Sunday in Bulgaria, where over 6,834,000 citizens are entitled to cast a ballot for a new President in an unexpectedly knife-edge race.

Maj Gen Rumen Radev runs as an independent, but is the de facto endorsement by the second-largest party in Parliament, the Bulgarian Socialist Party (BSP).

The distance between the candidates for president of GERB and BSP is closing. 31.4 % of voters would vote for Tsetska Tsacheva, while 27% would vote for Rumen Radev, showed a nationally representative survey of Mediana agency.

Bulgarian main ruling party's candidate Tsetska Tsacheva is set to lose to any of the two predicted frontrunners, a new survey has suggested.

With less than a week to go before the presidential elections in Bulgaria on November 6, the likely winner is proving difficult to predict.

Latest polls have shown that the successor to President Rossen Plevneliev, backed in 2011 by Bulgaria's governing centre-right GERB party, will not be elected in the first round on Sunday.