Last Thursday, as Podemos marked its fifth anniversary, party co-founder and chief strategist Íñigo Errejón stunned the Spanish left by announcing he would be running as the candidate for a new formation in the upcoming Madrid regional elections. Until then he had been committed to head Podemos’s own campaign for the powerful Madrid presidency.

But with negotiations deadlocked between Errejón and the national leadership over the makeup of his electoral list, the thirty-five-year-old chose to join forces with Madrid mayor Manuela Carmena’s new platform Más Madrid. This was then followed on Monday by his resignation as a member of the Spanish parliament, though he insisted he remained a member of Podemos.

Given Errejón’s increasingly fraught relationship with party leader and one-time close friend Pablo Iglesias, such a split was always possible. But the announcement caught the Podemos hierarchy off-guard. Errejón phoned Iglesias, who is currently on paternity leave, only minutes before the announcement with most of the leadership learning of the move through social media. In an open letter to Errejón released Thursday, Iglesias hit back claiming “the party membership deserved more” than such secret maneuvers and that he “could not believe Manuela and Íñigo [had] hidden their plans to launch their own electoral project.”