He was one of the main labor leaders of Vizcaya who laid the foundations for the founding of the historic Communist Party of the Basque Country.

Remaining a prominent leader of the PSOE until the beginning of the 20th-century, Perezagua came in to conflict with rising Indalecio Prieto, with whom he was competing for the leadership of the party in Biscay, over the question of alliance with the Republicans which he opposed.

[4] After the October Revolution, Perezagua together with the "terceristas" (left-wing of the PSOE) was in favour of adopting the "Twenty-one Conditions" for joining the Communist International.

However, after the end of the dictatorship he withdrew from the front line of Spanish politics, although he was a candidate for Vizcaya-capital in the legislative elections of 1933, in which the PCE ran alone, without obtaining representation.

He spent the last years of his life ill and isolated but remained a popular figure in the Spanish and Basque workers movement.