Borrisov's intention to call a confidence vote was revealed in a press release by the ruling party GERB (Citizens for the European Development of Bulgaria) made public late on Tuesday (18 January).
Borissov will ask parliament to support GERB for the government's overall activities. The decision was taken unanimously by the GERB leadership, the party said in a statement.
The move seems partly aimed at taking the Socialist opposition by surprise. Earlier, the Socialists said they would start consulting with other parliamentary parties on organising a no-confidence vote following the wiretap scandal.
In recent days, Bulgaria has experienced an avalanche of leaked wiretaps which first targeted the country's interior minister, Tzvetan Tzvetanov, but then focused on Prime Minister Boyko Borissov.
In one of those tapes, Borissov is allegedly heard speaking of the need to "protect" a controversial businessman from customs checks.
The wiretaps were apparently made by DANS, the country's national security agency, but were then leaked to Galeria, a tabloid with connections to Alexei Petrov, a controversial figure described by many as Borissov's most powerful enemy.
In an interview with EurActiv in February 2010, Borissov said his government was at war with the mafia, dramatically adding that the outcome of a high-profile anti-mafia operation in his country, dubbed 'Octopus', was still uncertain.
The most prominent personality arrested at the time for being part of an organised criminal group was Alexei Petrov, a former special forces member who infiltrated mafia circles, made a fortune there and apparently became a powerful political player. Petrov is currently under house arrest.
According to one of the tapes, Borissov instructs the country's customs chief, Vanio Tanov, to stop investigating a controversial businessman who owns a beer factory, stating he had "made commitments" not to harass him.
In other tapes, officials from the ruling GERB party speak of protecting businessmen who had been "paying" to stay outside state control.
The European Commission expressed its concern over the scandal and asked the Bulgarian authorities for information as to whether the wiretaps were made legally.
Asked by EurActiv whether Brussels was concerned about the fact that secret documents in Bulgaria were leaked to the press, a Commission spokesperson declined to comment.
Borissov leads a minority government, but has until now enjoyed the support of Ataka, a nationalist party, and of the Blue Coalition, a smaller centre-right political group (see 'Background').
