Partido Nacionalista Vasco, the Spanish acronym for the Basque Nationalist Party
In 1985 nevertheless, major divergences with the direction of his party (Law of Historical Territories, personal clash with the president of the Basque Nationalist Party, Xabier Arzalluz, expulsion of all the organization in Navarre) created a major split inside EAJ-PNV and Garaikoetxea, leading one of the factions (with greater support in Guipuscoa, Navarre and Vitoria-Gasteiz, but not in Biscay nor the Araban countryside), he was replaced by José Antonio Ardanza in 1985.
He was chosen in 1977 as a member of the regional council of the PNV in Biscay (Bizkai Buru Batzar), a position that he occupied until 1980 under the Presidency of Carlos Garaikoetxea.
In 1979, deputies (congressmen) Xabier Arzalluz of the Basque Nationalist Party (PNV) and Juan María Bandrés of Euskadiko Ezkerra, affirmed that Article 8 of the then-new Statute of Autonomy of the Basque Country was intended to integrate the enclave of Treviño into Álava and the enclave of Villaverde into Biscay.