Portugal just got a new prime minister and he's being propped up by radical left wingers and communists

Portugal has officially got a new prime minister.

Socialist party leader Antonio Costa has been named by president Anibal Cavaco Silva as the new PM on Tuesday, assuring that a new government backed by the country's far-left will take office.

Earlier this month, the Portuguese parliament passed a vote of no confidence against the government of Pedro Passos Coelho, who led a centre-right coalition after elections in October.

Portugal's centre-right parties won a combined 38.6% of the popular vote in the elections under the banner of "Portugal Ahead", but only held power for two weeks before being ousted.

President Silva previously sought assurances from Costa's coalition that he would stick to Portugal's EU budget rules if he came to power, but those assurances have now been given with a Socialist party statement saying the concerns were "duly noted".

The new government will be formed mostly of Socialist MPs, but will be propped up by the country's Communist Party and Left Bloc in a so-called "triple alliance".

"After hearing political parties with parliamentary representation, the president has decided to nominate Antonio Costa for prime minister," president Silva said in a statement on Tuesday.

The statement added that keeping Coelho's centre-right government in power would "not correspond to the national interest".