When the transplant takes place. The EAJ-BNP extends across the border

How did the Basque Nationalist Party (EAJ-BNP), a party of Spanish origin, spread to French territory? This article emphasizes that, very gradually, EAJ-BNP has become a full-fledged player in Basque political life in France. It shows that the proximity of a powerful autonomous power in the Spanish Basque Country, combined with an emerging form of decentralization in the French Basque Country, constitutes a favorable ground for the development of the party’s multi-level strategies. Above all, in Spain, the EAJ-PNB has established itself as the dominant party in the Basque political system, which legitimizes it in leading the national construction project beyond a European border that is permeable to this notion.