 In the 1933 elections he represented Carlism within the local Tarragonese Unió Ciutadana alliance and was successfully elected.As a result, he emerged one of key figures in the Levantine Carlism, especially in the comarcas of Terres de l'Ebre, though following the death of Jaime Chicharro also in Castellón.Voicing his support for the Catalan identity Bau has nevertheless opposed the adopted  as irreconcilable with the Spanish raison d'etat and produced by "traidores a su Patria y a su honor".