Further legitimacy was restored to Juan Carlos's position on 14 May 1977, when his father (whom many monarchists had recognized as the legitimate, exiled King of Spain during the Franco era) formally renounced his claim to the throne and recognized his son as the sole head of the Spanish Royal House, transferring to him the historical heritage of the Spanish monarchy, thus making Juan Carlos both de facto and de jure king in the eyes of the traditional monarchists.
On 20 May 1977, the leader of the only recently legalized Spanish Socialist Workers' Party (PSOE), Felipe González, accompanied by Javier Solana, visited Juan Carlos in the Zarzuela Palace. The event represented a key endorsement of the monarchy from Spain's political left, who had been historically republican. Left-wing support for the monarchy grew when the Communist Party of Spain was legalized shortly thereafter, a move Juan Carlos had pressed for, despite enormous right-wing military opposition at that time, during the Cold War.