A member of the Republican Federation, Ybarnegaray joined the French Social Party of François de La Rocque in 1938. He served as Minister of State in Paul Reynaud's government from 10 May 1940. On arrival of refugees from the Basque (1937) and Catalan fronts (1939) in the Spanish Civil War, Ybarnegaray took a hostile stance against the exiles, labeling them as "reds" and turned a cold shoulder to Basque nationalism or any Basque political approach.