Since the end of the Franco dictatorship in the mid 1970s, Spanish national politics has largely been dominated by two political parties: the conservative People's Party (PP) and the Spanish Socialist Workers' Party (PSOE). Yet that all changed after the general election on December 20, 2015, when two relatively new parties – the left-wing, anti-austerity Podemos (We Can) and the center-right Ciudadanos (Citizens) – collectively received a quarter of the votes.

Since the current ruling party, the PP, led by Prime Minster Mariano Rajoy, won only 123 seats in the 350-seat Congress of Deputies, it fell well short of the 176-seat majority needed to stay in power. Now, the political parties have begun talks trying to assemble a governing coalition.

The PP would like to ally with Ciudadanos, but since the latter received only 40 seats, together, the parties would need the support of some of the smaller regional parties in order to form a majority – a difficult task given that the largest regional party, representing Catalonia, supports that region's independence from Spain.

There is also the possibility of left-wing coalition comprised of the PSOE, which won 90 seats, and Podemos, which won 69 seats, but since the latter supports holding a referendum on Catalonian independence, it is not a natural partner for any of the three major parties, which prefer maintaining national unity.

A third possibility is the formation of a PP-PSOE "grand coalition," but given the animosity between PSOE leader Pedro Sánchez and PM Rajoy, this alliance seems unlikely. In short, it may take weeks – and perhaps another election in the spring – before a new government is formed.

Despite this uncertainty, it is still possible to draw some analogies between contemporary Spanish and American politics, and even to extract some lessons from the recent election about how to disrupt a seemingly entrenched two-party system.

At first, it may seem unjustified to compare the two countries: seats in Spain's lower house are allocated on the basis of proportional representation in accordance with the outcome of elections in 50 multimember districts, whereas the United States uses the plurality voting method in single-member districts to determine the composition of the House. Nevertheless, there are significant political and economic similarities between the two countries.

Economically, Spain – much like the United States – is still recovering from the Great Recession. There, unemployment reached as high as 27 percent following the crash in 2008, and today it hovers around 20 percent. While there has been growth in recent years, and growth is forecasted for 2016, discontent with the government's handling of the economy is still high – especially among Spanish youth, for whom employment is nearly 50 percent.

Also, politically, there is waning trust among the public for the political establishment, as the PP and PSOE have been embroiled in corruption scandals in recent years.

It is under these economic and political conditions that – much like in the United States – populist movements and candidates on the left and right have thrived. Podemos indicates that its goal is to move beyond "left" and "right" and instead seeks to empower those from "below" in order to challenge those "above." Ciudadanos also expressed its anti-establishment bona fides when its leader Albert Rivera stated his reluctance to form a coalition with the PP or PSOE because they "represent a way of doing politics from the past."

But what most separates the Spanish from the American situation is the decision by the populist movements in Spain to organize and mobilize voters outside the two major parties.

Podemos, for instance, is an outgrowth of the Occupy Wall Street-like indignados protest movement that began in 2011. Though Podemos was created only in 2014, it has already won more than 100 seats in regional parliaments and seated mayors in Barcelona and Madrid.

Likewise, Ciudadanos was founded in 2006 at first to challenge Catalonian nationalism, but later expanded its platform, made anti-corruption a central message, and spread its reach across Spain. In 13 regional elections in 2015, it won over enough PP supporters to deprive the PP of an outright majority in eight of them.

Also in contrast to the United States, Spanish voters in the latest general election showed that they were no longer willing to be persuaded – despite efforts by the PP and PSOE – to succumb to the logic of the "wasted vote" and support "the lesser of two evils."

For example, the PP's campaign director, Jorge Moregas, tried to portray the youthful leader of Ciudadanos, Albert Rivera, as inexperienced and incompetent, and he warned that supporting the insurgent party would empower the left-wing opposition. Similarly, a former PSOE official tried to discredit Podemos by implying that it was a "neocommunist" force, and another leading PSOE figure accused Pablo Iglesias' party of naively offering "incoherent and unrealisable” proposals.

Despite these caveats, many Spanish voters have evidently decided that they have had enough of their two-party system. Rather than work within the two major parties, populists have, through persistent organization and mobilization, created legitimate alternatives to the PP and PSOE.

In the United States, where populist movements like the Tea Party and Occupy Wall Street and the popularity of "outsider" presidential candidates have shown that many Americans are dissatisfied with establishment politics, it is worth exploring if, when, and how they will be able to join Spaniards in exclaiming, "El bipartidismo ha muerto" – "The two-party system is dead."

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