Why did Pablo Neruda move closer to communism while living in Spain?

While living in Spain during the 1930s, Pablo Neruda moved closer to communism primarily through his social circle. After being transferred to the consulate in Madrid, he befriended poets such as Rafael Alberti and Miguel Hernández, who were deeply involved in radical politics and the Communist Party.1

Sharing their political convictions, Neruda began to shift his poetic focus away from hermetic, personal themes toward a more extroverted style intended to communicate social concerns. This ideological evolution was further solidified by the outbreak of the Spanish Civil War in 1936. Witnessing the conflict firsthand, Neruda expressed his solidarity with the Republicans through his writing and activism, eventually leading to his formal commitment to left-wing ideology and his later membership in the Communist Party.1