Voters began casting ballots yesterday across much of Spain in local elections that could see two upstart parties end nearly four decades of dominance by the ruling conservative Popular Party and its rival, the centre-left Socialists.

At stake are 8,122 town halls as well as parliament seats in 13 of Spain's 17 regions. More than 35 million Spaniards are registered to vote.

Opinion polls indicate voters are fed up with Spain's economic downturn and the corruption scandals that have rocked both main political parties, which have alternated in power.

That dissatisfaction has opened the door to the centrist, pro-business Citizens party and the left-wing We Can party - both relative newcomers that began operating on a national scale only last year.

The two most important electoral battlegrounds will be for control of the capital - Madrid - and for Barcelona, the regional capital of the relatively prosperous but heavily indebted northeastern Catalonia region.

In Madrid, where protesters angry with austerity measures and corruption camped out in the Puerta del Sol square for weeks in 2011 and helped fuel the worldwide "Occupy" movement, the Popular Party could lose its long-standing majority.

The We Can group was born out of that Madrid protest, which railed against the stinging cutbacks introduced by Prime Minister Mariano Rajoy's Popular Party and the widespread mismanagement that led to a bailout for Spain's banking sector after the country's once-thriving real estate sector collapsed.

In Barcelona, a popular anti-eviction advocate backed by We Can could upset the region's long-dominant conservative Convergence and Union party.

Polling booths close at 8 p.m. with final results expected by midnight.

Sunday's vote is Spain's 10th local election since democracy was restored 36 years ago after the military dictatorship of Gen. Francisco Franco.