It looked increasingly likely this week that Pedro Sánchez, winner of April's general election with his PSOE party, would not secure a majority of MPs' votes to be the next prime minister in July's investiture debate in the Congreso.
Sánchez, who is acting PM in the meantime, has been in negotiations with Unidas Podemos to add the support of its MPs to his own 123. Sánchez wants a government of collaboration, with second-level ministerial jobs going to some Unidas Podemos members. However, leader, Pablo Iglesias, is holding out for some full ministerial positions.
The Partido Popular and Ciudadanos parties have refused to abstain in the investiture debate due in mid-July to allow in a minority PSOE government.
Unidas Podemos said this week that they believed Sánchez would fail in the July vote and renegotiate with them to secure a government in another, September vote.