Basque backing for Gibraltar is symbolic of wider support

The leader of one of the Basque nationalist parties has suggested that Gibraltarians may regard British sovereignty as providing greater guarantees for the protection and respect of their rights. This, in his view, accounts in part for the decision to remain British and for our refusal to become a part of Spain. 

Arnaldo Otegi, who is the coordinator of Euskal Herria Bildu, set out his reasoning on Gibraltar to advance his own argument that there would be Spaniards in the Basque Country who might feel their rights would be better upheld by an independent republic than they are presently as part of Spain. The party, more generally known as EH Bildu for short, has been one of the nationalist groups who have supported Prime Minister Pedro Sanchez with their votes in the Spanish Parliament.
Bildu holds 5 seats in the Congress in Madrid as well as 21 of the 75 seats in the Basque Parliament. They have one seat in the European Parliament where they sit with the group of the Left known as GUE/NGL.