On 31 December 1920, Antón married for the second time, this time marrying the sister of his first wife, Mercedes Espinosa Cervela, with whom he had six more children.  1917 was to be fundamental in the political path of Losada since he became a member of the Irmandades da Fala. On 17 October, he wrote to requesting information and, by 30 October, he had already been integrated into the Irmandade. During that year, he traveled to Barcelona with a delegation of the Irmandades to celebrate a Galician Week and got in contact with the Lliga. When Antón went back to Ourense he was responsible for receiving Francesc Cambó, and was responsible, with and Lois Porteiro, for organizing the Galician autonomy candidatures in the province of Ourense for the Spanish general election held in 1918, in coalition with the mauristas of José Calvo Sotelo. The electoral defeat caused demoralization in the Irmandades and Losada concentrated his efforts in consolidating the group. In order to do so, he wrote many articles in the press, especially in "", "La Región", "", "A Nosa Terra", "" and "" wherein his writings in Galician could be found, and at the same time continuing his work as Catholic propagandist in Pontevedra acting as president of Catholic Action and of the local Circle of Catholic Workers venues. He also tried to promote some of the first shy attempts have the Galician language adopted in the liturgy. He even translated Salve Regina into that language. In November 1918, he chaired the . Along with Risco and , in 1920, he founded the "Nós" magazine. He accompanied Risco in the training of the Irmandade Nazonalista Galician during 1922 and was his Propaganda Minister for a year, failing in his attempts to reunify the galeguismo movement. On May 12, 1924, Antón Losada became a member in the Seminar of Galician Studies with the speech "Ouservacións encol da prosa galega". In reliance on Calvo Sotelo's promises, Losada collaborated initially with the Primo de Rivera dictatorship, as a provincial deputy in Pontevedra. During that period, Antón took part in the failed attempts to establish a Mancomunity of Galicia, leading to his capitulation at the beginning of 1925. During the rest of the dictatorship, he participated in cultural activities such as founding the Choral Polifónica of Pontevedra, the Eiriña Football Club and his work in the Seminario de Estudos Galegos, but without forgetting the aspirations for autonomy for Galicia.