Maps of municipal elections in Spain in 2011 vs. the recent 2015 elections show a remarkable change in leadership.
 

click on chart for sharper image

• PP - Blue - People's Party - Party of Prime Minister Mariano Rajoy
• PSOE - Red - Spanish Socialist Workers' Party - typically the largest competitor in what was once primarily a two-party system, but is no longer
• PNV - Green - Basque Country
• CiU - Yellow - Convergence and Union
• Podemos - Purple

The alliances are very complex, but note the rise of Podemos (purple).

Also recall that the Podemos "Economic Manifesto" Calls for Debt Restructuring, Spain to Abandon the "Euro Trap".

I believe Podemos has tempered some of those claims (possibly an election ploy), but party leader, Pablo Iglesias, is very close friends with Greek Prime Minister Alexis Tsipras.

For the first time in 24 years, PP did not carry the vote in the Madrid municipal election. Instead, Manuela Carmena, a Podemos-backed, anti-austerity candidate is now Madrid's new mayor.

National Elections This Year

Spanish national elections are this year (on or before December 20), with no date set as of yet.

The most likely dates are purported to be October 25 or a Sunday in November other than November 1, All Saints Day, a religious holy day for Catholics.

Election Outlook

At this juncture it is impossible for any party to get a majority of votes.
So what happens?

Wikipedia reports on  2015 Spanish Election details.

Unlike other neighboring countries' practice, such as Portugal, Greece or Italy, elections in Spain that result in hung parliaments rarely result in coalition governments at the national level. Rather, the party with the most seats has historically formed a minority government with the confidence and supply support of other parties, relying on legislature pacts or, in the event of a party holding a working majority (not absolute but large enough to govern on its own right), ad hoc agreements and/or variable geometry pacts, in order to pass legislation through the Congress.

Opinion Polls

This could get very interesting, especially if Podemos can pull off an upset. And it won't even be that much of an upset according to recent opinion polls.

click on chart for sharper image

It's very conceivable that an anti-euro party will find itself in power, in Spain, later this year!