Whilst Mr Borissov, and his centre-right GERB party, are expected to emerge as the largest faction they may struggle to put a governing coalition together. Fury over corruption scandals looks set to allow a number of smaller populist parties into parliament.
Sofia, the capital of Bulgaria, was rocked with protests last year following corruption allegations against Mr Borissov.
He has largely avoided the media instead focusing his campaign on the countryside with promises of more jobs.
Preliminary polls indicate GERB took 29 percent of the vote with the opposition socialists 5-10 points behind.
This would give Mr Borissov 76 seats in Bulgaria’s 240-seat parliament.
Third place is expected to be taken by an insurgent party launched by a popular Bulgarian entertainer.
Speaking to AFP election analyst Antony Todorov predicted as many as six parties could win seats.
He commented: “It’s the absence of an alternative due to the fragmented and unconvincing opposition that explains GERB’s hegemony.”
However he warned GERB could still find it difficult to form a stable government.
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Before the election Boriana Dimitrova, warned the election result is likely to be messy.
Speaking to Politico he said: “We are likely to see a very fragmented and disparate parliament, comprised of up to six or seven parties.
“We expect to see some new political players, whose policies remain a mystery at the moment.”
Daniel Smilov, a political analyst at the Centre for Liberal Strategies, gave a similar prediction.
He warned: “We might have to opt for a technocratic government where no single party has the upper hand.”
Bulgaria is currently suffering from another coronavirus wave which threatens to overwhelm hospitals in the country.
Analysts predicted this would decrease election turnout, potentially to the benefit of Mr Borissov.
As an EU member Bulgaria is reliant on the European Commission for its coronavirus vaccines.
Brussels was slugging at acquiring jabs meaning the vaccination programmes of EU members are lagging significantly below the UK.
Officially Bulgaria has recorded 13,500 coronavirus deaths since the crisis began.