Local elections in Spain test upstart parties' voter appeal, ability to threaten heavyweights

Pablo Iglesias, the leader of Spain's new and growing left wing 'Podemos' (We Can) party speaks during a meeting with supporters for the upcoming local elections in Madrid, Spain, Friday, May 22, 2015. Spain could be set for a political upheaval in key local elections this weekend, with strong signs that voters fed up with economic crisis and corruption scandals may punish both the ruling conservative Popular Party and the leading opposition Socialists. (AP Photo/Andres Kudacki) (The Associated Press)

Pablo Iglesias, right, the leader of Spain's new and growing left wing 'Podemos' (We Can) party, stands with Podemos candidate for President of the Community of Madrid Jose Manuel Lopez, as they salute the crowd during a meeting with supporters for the upcoming local elections in Madrid, Spain, Friday, May 22, 2015. Spain could be set for a political upheaval in key local elections this weekend, with strong signs that voters fed up with economic crisis and corruption scandals may punish both the ruling conservative Popular Party and the leading opposition Socialists. (AP Photo/Andres Kudacki) (The Associated Press)

Supporters clap their hands as leaders of the Spain's new and growing left wing 'Podemos' (We Can) party speak during a meeting for the upcoming local elections in Madrid, Spain, Friday, May 22, 2015. Spain could be set for a political upheaval in key local elections this weekend, with strong signs that voters fed up with economic crisis and corruption scandals may punish both the ruling conservative Popular Party and the leading opposition Socialists. (AP Photo/Andres Kudacki) (The Associated Press)

Local elections in much of Spain could see two upstart parties end nearly four decades of dominance by the conservative Popular Party and the center-left Socialists.

At stake in Sunday's vote are 8,100 town halls as well as parliament seats in 13 of Spain's 17 regions.

Opinion polls indicate voters are fed up with Spain's economic downturn and the corruption scandals that have rocked the ruling Popular Party and the opposition Socialists, 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.

Polling booths open at 9 a.m. and close 11 hours later, with final results expected by midnight.