 Though dictatorship was initially welcomed by the Carlists as a stepping stone towards a Traditionalist monarchy, in 1925 the claimant Don Jaime switched to opposition.Bau decided not to follow suit and went on contributing to the regime; in literature he is usually listed along Victor Pradera and Esteban Bilbao as one of those Carlists who abandoned their king and joined the primoderiverista version of the Alfonsine monarchy.In 1927 he was appointed to the quasi-parliament, , standing as representative of Organizaciones provinciales de Unión Patriótica and representative of the Ayuntamientos; in the chamber he became one of the youngest members.