This is the fourth time that Socialists try to oust the centre-right minority government of Prime Minister Boyko Borissov, who is propped up in parliament by a right-wing party.
Debates on the motion are expected to start within a week, according to a Bulgarian news agency Focus. If the vote fails, a new one can only be held in six months.
Leftists accuse the government of mismanaging waste processing and allowing the only water source in the city of Pernik to be used for industrial purposes. This has led to water rationing and arrest of the environment minister.
