Last week’s disappointing election result has exposed a fissure on the Spanish far left.

The debate is a predictable one: hardliners insist the Podemos alliance with the communist-led United Left wasn’t left-wing and principled enough; moderates recognize that it was perceived as too radical.

Preelection polls had shown Podemos surpassing the mainstream Socialists to become the biggest party on the left. But on election day, they got exactly the same number of seats as they did in December. The Socialists lost five but still came in second.

The outcome was especially bitter because Podemos had teamed up with the United Left in order to grow its parliamentary faction. It effectively lost seats, because the United Left’s were folded into Podemos.

Blame game

Podemos leader Pablo Iglesias and the United Left’s Alberto Garzón have defended their alliance, arguing that the result would have been even worse if they had run separately.

One of the co-founder of Podemos, Juan Carlos Monedero, has blamed a lack of ideological authenticity while Íñigo Errejón, the party’s number two in parliament, has blamed the alliance with the United Left.

Errejón has often been a voice of moderation in the parliamentary party.

Find the center

All this will sound familiar to members of the Labour Party in the United Kingdom or to Republicans in the United States.

Britain’s far left believes Labour lost the last two elections because it didn’t campaign convincingly against austerity. Surveys have consistently shown the opposite: that voters in the middle didn’t trust Labour not to plunge the nation in the red again and ruin the economy.

(Spain’s Mariano Rajoy actually made the same argument to voters as Britain’s David Cameron did last year: the left can’t be trusted to run the economy, I am the one with a serious plan. It’s not exciting, but it works.)

Hard-right Republicans in the United States similarly argue that the reason they lost the last two presidential elections is that they nominated “moderate” candidates. John McCain and Mitt Romney may have been relatively moderate; voters in the middle still saw them as in thrall to a party that has drifted further and further to the right.

In most Western countries, most of the time, elections are won in the center. Spain is no different. The choice for Podemos is clear: make itself electable at the expense of ideological purity or accept it might be permanently in opposition.