Bulgaria's president gave Thursday the Socialists a mandate to put together a government after the winner of this month's elections, conservative ex-premier Boyko Borisov, conceded forming a cabinet was impossible.
Borisov's GERB party fell way short of a majority in the May 12 election, held three months after anti-poverty and corruption protests in the European Union's poorest country prompted the former bodyguard's resignation.
Earlier Thursday he formally returned the presidential mandate, saying: "I apologise to our over one million voters, who expected us to form a government... but there is no way to pass our proposed cabinet through parliament."
The Socialists, who came second with 84 seats to GERB's 97 in the 240-strong parliament, aim to form an anti-crisis technocrat government led by former finance minister Plamen Oresharski.
"I will do everything possible to present parliament in the shortest time with a proposal for the composition of a cabinet," the non-partisan Oresharski said upon receiving the mandate from President Rosen Plevneliev.
The Socialists have already won backing from the Turkish minority party MRF, which has 36 lawmakers, while the ultra-nationalist Ataka party, with 23 MPs, was also likely to give it silent backing to avoid new elections.
The technocrat government is expected to be put to the vote next Tuesday and would only need a simple majority for approval, which can be achieved even if Ataka boycotts the vote.
Oresharski has outlined a package of social measures to combat growing poverty and unemployment and vowed to work for re-starting the stagnating economy by improving the business environment.
Analysts however predicted that changes will not come soon enough for the government to last longer than six months to a year, particularly since it will have to rely on the unpredictable Ataka to pass legislation.