In 1931 he was exiled to Easter Island by dictator Carlos Ibáñez del Campo for his leftist political activity.

After Ibáñez's fall later that year, he was able to return to the Santiago and co-founded the socialist Nueva Acción Pública (New Public Action), with Colonel Marmaduke Grove, among others.

[2] In June 1932, he was involved in the coup that ended the reign of President Juan Esteban Montero.

Within the junta, disagreements soon arose between moderate and radical forces, with Matte and Grove clearly belonging to the latter group.

The moderate socialist Carlos Dávila, on June 16 with the cooperation of several officers, organized a new coup d'état and had radical junta members, including Matte and Grove, interned on Easter Island.