Proposals for voting strategies proliferated in the runup to Sunday's general election in Spain. People wrote "ballot box" on drains and toilets; others suggested cutting out the middlemen and depositing votes directly into bank machines. This campaign of ballot spoiling wasn't a subcultural anarchist prank, but a reflection of extraordinarily widespread popular disaffection. A typical sight during a pre-election protest was a respectable middle-aged man with a cigarette in one hand and a marker pen in the other going from municipal bin to municipal bin writing "Vote here" on the lids."They don't represent us" and "They are all the same" – the slogans of the indignados (the Spanish progenitors of the Occupy movement, who have mobilised hundreds of thousands across the country) – are now mainstream.

In contrast to the political parties, the indignados (the "outraged") say: "They want your vote; we want your opinion." They question the very legitimacy of electoral politics, seeing a hollowing out of representative democracy that the eurozone crisis is rendering critical. In their words, "the polls are in the safe custody of the European Central Bank".

On election day the indignados got protest-voting trending on Twitter with a three-pronged strategy: to abstain, spoil one's ballot, or attempt to break out of the bipartisan system by voting for a minority party. Rather than just staying at home, people actively registered disgust at the choices on offer, and the number of spoiled ballots on Sunday was double that of the last election in 2008 – numbering, with abstentions and blank votes, 11 million: more than voted for the rightwing victors, the Partido Popular.

Electoral disaffection reflects the harsh economic climate of Spain, with an unemployment rate of 46% for those under 30. Since the crisis voters have seen the socialist PSOE government renege on social policies and adopt the harsh austerity programmes of the right; as with New Labour, its traditional voter base turned away in disgust. It wasn't so much a case of the PP winning a mandate on Sunday, but of the PSOE losing 4.5 million voters.

Meanwhile the rhetoric of the indignados – that democracy is being eroded by the markets – has received unwelcome validation as the world of finance pummels Spain. Just before the election, borrowing costs had jumped to a 14-year high. In the words of Carlos Delclós, a Barcelona indignado: "[The incoming prime minister] Mariano Rajoy's task, at this point, is to try to guess what Merkel or the IMF want him to do before they tell him, so that his decisions look more like his own brilliance, and not the imposed will of dominant supranational institutions. The movement knows this, and I don't think they're going to be fooled into thinking that these elections change anything besides, perhaps, the scale of repression the government is willing to impose."

Leónidas Martín, artist, activist and professor at the University of Barcelona echoes this concern: "The results are perverse, a reflection of the disaffection with democracy." Martín perceives a real danger in this popular disaffection, however. He is "worried by the model of technocratic governments imposed by the markets as in Italy and Greece," he says, because "the markets are incorporating the popular disaffection into their own interests. They say: 'You don't like politicians? You don't like democracy? Very well, we understand you, and we want to help you. Just leave everything to us. We are experts.'"

In the short term, the reality of a rightwing government may well dampen the mood of the indignados. But it is also setting the stage for a massive new wave of protest that will strengthen the movement. By next spring those made unemployed by the crisis will start running out of unemployment benefits. This, combined with stringent new austerity measures and angry unions – whose hands had been tied by their connections to the socialist government, but can now come out fighting – will usher in what looks to be an enormous and potent wave of direct action.

The indignados are playing the long game. Inspiring Occupy tactics in other countries, they have been taking over empty bank-owned properties across the country from Galicia to Andalucia and Madrid to Barcelona. The general assemblies of the encampments they held in the summer are now devolved to local neighbourhoods; the occupied buildings are being used to hold assemblies through the winter months and house those evicted through mortgage defaults. "The answer to the crisis is not apathy or cynicism," says Kike Tudela, a historian and activist. "We have four years of struggle and resistance ahead, and the question is: what will we have after four years? Do we want the socialists back with more neoliberal policies, or something new?"

The indignados are now exploring ideas that go far beyond party politics or even changing electoral law, such as participatory budgets, referendums, election recalls and other forms of citizen-initiated legalisation. "It's a debate we have to have within the movement, but perhaps we can create new political forms from below. We are interested in Latin American models," Tudela says, referring to governments that have resisted the onslaught of neoliberalism in tandem with social movements that hold them to their promises.

This new form of politics that creates effective pathways between social movements and government is vastly ambitious. But as the indignados say: "We are going slowly, because we are going far."