Spain's big vote

Outside a municipal sports building in Alcala de Henares, a small city east of Madrid, crowds are gathering and clusters of balloons are bobbing in the breeze. Just ahead of local elections across Spain, supporters of the new party, Ciudadanos, or "Citizens," are in high spirits, believing that its phenomenal rise in recent months will soon make it one of the country's most prominent political forces.

Inside, a few minutes later, the party's 35-year-old leader, Albert Rivera, bounds onto the stage to deliver a powerful message to his electoral rivals.

"Some don't understand what is happening in Spain - we're not just facing an election day, we're facing a new era," he says. "Whoever can't understand that isn't capable of leading the change. Spain is not doing well, it's only doing well for a few."

This promise by a generation of young Spanish politicians to deliver a "new era" has already altered the country's political landscape. But on Sunday, when elections are held for control of town and city halls across Spain and for 13 of its 17 regional parliaments, the political map is expected to be drastically redrawn.

Spain's two-party politics

For the last three-and-a-half decades, the conservative Popular Party (PP) and the Socialists have dominated Spanish politics in a rigid two-party system. But the recent economic crisis and a torrent of corruption scandals have threatened to break that duopoly for the first time in Spain's democratic period. Ciudadanos and another new party with a young leadership, Podemos, or "We Can" in Spanish, are the beneficiaries of Spaniards' disenchantment with the status quo and national polls show them in a four-way virtual tie with the PP and the Socialists.

"This election represents a revolution because we're going to go from having just two parties which are capable of governing, to having a political map on which there are four parties, all of which are capable of governing," says Jose Ignacio Torreblanca, a political scientist who recently published a book about Podemos.

The sudden nature of the rise of both Ciudadanos and Podemos has made this development all the more dramatic.

Podemos was formed in early 2014 by a group of left-leaning university professors. After scooping 1.2 million votes in the EU elections a year ago, its support continued to swell, until it was leading some national opinion polls early this year. Led by the 36-year-old Pablo Iglesias, it has declared close links to Greece's Syriza party and its anti-austerity, anti-corruption, platform reinforced the comparisons.

The Podemos of the right?

But in recent months polls have shown support for Podemos dipping. Some have attributed this to the party attempting to present a more moderate image, while others believe it has been hurt by the rise of Ciudadanos.

The latter was founded in 2006, as a Catalan party that opposed regional nationalism, before expanding its presence to become a nationwide party earlier this year. Its focus on battling corruption while proposing liberal economic policies has led many to label it "the Podemos of the right."

This is a description that Ciudadanos's candidate for regional premier of Madrid, Ignacio Aguado, roundly rejects.

"We propose a change, but a sensible change," he said, speaking shortly before his party's rally in Alcala de Henares. "We are a sensible choice for change. Podemos from my point of view is a political party that is proposing a break with the past. It's looking back to the past. We prefer to look ahead to the future and try to understand the global economy and global society."

The governing Popular Party has been trying to undermine the message of these new parties by focusing its campaign on the fact that the country's economy is expected to grow nearly 3 percent this year, a far cry from 2012, when Spain's deficit, debt and banks were the focus of the euro-zone crisis.

"Who today talks about recession, bailouts and unemployment?" Prime Minister Mariano Rajoy declared in Pamplona this week as he sought to win over undecided voters.

Outrage refuses to fade

But the widespread anger at the country's politicians and bankers which fuelled the rise of Ciudadanos and Podemos has not disappeared. Unemployment is falling but is still at nearly 24 percent, with around half of young people out of work. Also, families are regularly being evicted from their homes for failing to keep up mortgage payments.

The refusal of many Spaniards to accept the government's message of recovery helps explain why, for example, polls show Podemos - in a leftist coalition - vying with the PP for victory in Madrid city hall.

"[The PP and Socialists] have proved to be inefficient and incapable of implementing a national vision that guarantees a dignified future for the social majority," says Miguel Vila, a 30-year-old Podemos candidate for the Madrid regional parliament.

"The main problem is these two big parties, because they have governed for the interests of the privileged minority - their friends," he says. "And also corruption, because let's not forget that Spain is a corrupt country, from the first institution to the last."

These local elections are expected to be followed by a general election later in the year, which is likely to confirm that Spain has decided to jettison a longstanding two-party system and embrace a message of democratic regeneration.