Spain’s two left-wing parties need to decide if they want to stick to their principles and keep their hands clean — or if they’re willing to make compromises in order to get into power.

At a party conference this weekend, members of the anti-establishment Podemos movement are asked to endorse one of two visions: either stay the hard-left course under Pablo Iglesias, the current leader, or switch to the more pragmatic policy of his deputy, Iñigo Errejón.

The mainstream Socialists face a similar choice in their leadership election. Patxi López and Pedro Sánchez advocate opposition to the minority right-wing government of Mariano Rajoy. Susana Díaz, the president of Andalusia, represents the moderate wing of the party, which argues against blowing up an accord that has kept Spain governable since October.

The outcome of the struggle in Podemos could have an effect on the Socialist Party contest later this year.

Sánchez in particular, who was the party leader until October — when he was forced out by regional bosses like Díaz — believes the Socialists must take the fight to the right in order to consolidate their left flank.

Infighting

Errejón and Iglesias appear to have remained on speaking terms despite their differences, but their supporters are pulling no punches. Several top Podemos figures have resigned in the last few weeks. Some on the far left of the party, for whom even Iglesias is too soft, are talking about splitting off.

At the heart of the Errejón-Iglesias dispute is a basic question that has marred Podemos from the start: whether to stay true to its leftist principles, knowing they will never be embraced by more than a quarter of the electorate, or compromise for the sake of power.

That disagreement came to a head when neither Rajoy’s conservative People’s Party nor the Socialists, then led by Sánchez, won a majority in the December 2015 election.

Sánchez did a deal with the liberal Ciudadanos to reverse part of Rajoy’s austerity program. Errejón saw an opportunity for Podemos to help keep the right out of power, but Iglesias vetoed a pact with the center-left.

Without the support of Podemos, Sánchez and the Ciudadanos fell short of a majority and new elections were held in June 2016.

For those elections, Iglesias led Podemos into an alliance with the communist-led United Left, hoping to best the Socialists this time.

It didn’t work. The far left lost around one million votes. Leftwingers switched to the Socialists, who, in turn, lost centrist voters to Rajoy. After several more months of fruitless coalition talks, the Socialists removed Sánchez and acquiesced in the formation of a right-wing government.

Time for compromise

Díaz and the Socialist Party machine know that Middle Spain isn’t keen on another election. The economy is humming along, with growth over 2016 coming in at 3.2 percent. The time when Spaniards might have been tempted to try radical new policies has passed.

Rajoy isn’t loved. But he is seen as a steady hand while voters dislike the infighting on the left.

In the last two elections, the Socialists and Podemos won far more votes combined than the People’s Party did on its own: more than ten million against seven to eight million for Rajoy.

The only way the Socialists win is by taking centrist voters away from the conservatives. The only way they could justify a coalition with Podemos is if the latter is willing to compromise on issues like canceling Spain’s debt and nationalizing industries.

If the parties are serious about taking power, they will turn to Díaz and Errejón. If they prefer to keep their hands clean in opposition, they ought to stick with Sánchez and Iglesias.