Residents in Spain have begun voting in a third general election in four years.

All eyes are on whether the rise of conservative nationalism will allow the right wing to unseat the incumbent prime minister.

Pedro Sanchez is set to win the most votes, but his Socialists seem far from securing a majority in parliament to form a government on their own.

Spain Election
Spanish Prime Minister and Socialist Party candidate Pedro Sanchez casts his vote (Bernat Armangue/AP)

The fragmentation of the political landscape is the result of austerity that followed the economic recession, disenchantment with bipartisan politics and the recent rise of far-right populism.

Mr Sanchez called Sunday’s ballot after a national budget proposal was rejected in the Lower Chamber by the centre-right-conservative opposition and Catalan separatists pressing for self-determination in their north-eastern region.

Voting stations opened at 9am local time and will close at 8pm, with results expected a few hours later.