Eight months ago nobody would have expected it. After an internal coup forced him to resign as leader of Spain’s Socialist Party (PSOE), Pedro Sánchez seemed politically dead. Even his closet allies within the party had abandoned him. But after turning to the left in recent months, he secured a resounding victory in the party’s leadership race on May 21.

In the contest he defeated Susana Díaz, one of the key figures in the heave against him and a prominent right-winger with the backing of the powerful PRISA media group. The victory, by more than ten points, saw Sánchez secure an outright majority and win in all but two of Spain’s seventeen autonomous regions.

The story of the campaign was a rebellion by PSOE activists angered by the party’s decision to return their historic adversary, the Popular Party, to power. Unlike most of the PSOE hierarchy, Sánchez had refused to back a policy of abstention in the vote on Prime Minster Mariano Rajoy’s investiture. This stance, as well as his forced resignation, allowed him to position himself as the anti-establishment candidate defending social-democratic values against the party machine.