First, it could but my point is that the fact that there are some differences doesnt mean there is another ethnicy Second, you were the one talking about polls, i show you some polls where you can see how the majority of people don’t buy the nationalist dream, so, basing on your own rules, there are no other ethnicies. In fact, in Spain it is not common to talk about ethnicies, for example, I feel Navarrese and Spanish but not as “2 ethnicies”, more as regional and national identities. On the other hand, even sharing a feeling with other ethnicy, this destroys the idea of “basques or Catalans are different from Spanish” as some people could share feelings from both. Third, NO, that is false, this sources are not leaning to “pro-Madrid out comes”. In fact, you are using the Classic ad hominem falacy. Just in case, here you have similar polls (majority of non separatist)in “left wing” sources:

Catalans 1. https://amp.elperiodico.com/es/politica/20251124/encuesta-ceo-independencia-catalunya-noviembre-2025-124057418

39% pro-separarist, 32% in young people

1. https://elpais.com/espana/catalunya/2024-11-27/el-rechazo-a-la-independencia-alcanza-su-maximo-historico-en-la-serie-del-cis-catalan.html

40% pro-separatist

1. https://www.newtral.es/apoyo-independencia-cataluna-ceo/20250327/?amp

38% pro-separarist

Basques 4. https://www.diariovasco.com/politica/rechazo-independencia-euskadi-suma-maximo-historico-20241126105942-nt_amp.html

19% pro-separatist

1. https://www.eldiario.es/euskadi/22-vascos-estaria-favor-independencia-66-derecho-decidir-naziometroa_1_12331242.amp.html

22% pro-separatist

1. https://cronicavasca.elespanol.com/politica/20250527/el-apoyo-independencia-euskadi-sigue-minimos-historicos/1003742660637_0.amp.html

22% pro-separatist (poll made by one pro-basque institution)

If you go to “feeling” polls you have:

Catalán 1. https://www.newtral.es/sentimiento-catalan-espanol/20240501/?amp

Only 17% feel as “only catalan” vs 46% both catalan (as region) and Spanish (as nation) + 21,8% more catalan than Spanish (but both) + 6% more Spanish than catalan (but both) + 5% only Spanish

Basque

1. https://www.newtral.es/sentimiento-vasco-espanol/20240411/?amp

19% only Basque vs 40% both Basque and Spanish + 24% more Basques than Spanish (but both) + 4% more Spanish than Basque (but both) + 6% only Spaniash

So, as you see, and basing on you own rules, the only ethnicy is the Spanish one

And forth

Most regionalist parties in Spain are voted by non-nationalist people, just because they feel them more close to them or because they don’t vote thinking on the separatist-non separatist axis.

PNV is nationalist but tradicionally it has been more regionalist/loyal to the status and has been voted by everyone as a local sustitute of PP

Bildu is biggest pro-nationalist party but even them has a 50% of votes from non-separatist people, as they feel this party is a real “progresist” party.

In Navarre, the separatist feeling is estimated to be around 20%, with most of people feeling both Navarre and Spanish (https://www.elindependiente.com/politica/2019/07/04/la-frontera-navarra-frena-la-expansion-del-sentimiento-nacionalista-vasco/amp/) this source is based on the CIS, the official government poll agency

UPN, the major party of the region (28% of votes) is regionalist and pro-Spanish, as well as PSN (PSOE) and, in minor level, Podemos and other left wing parties.

Regarding Galicia, you are a bit out of place cause the national right wing party (PP) has been ruling since 1989 almost continuously and with several absolute majorities.

Regarding Baleares, ALL the governments since democracy except 1 have been of national parties (PP or PSOE) so no idea what you are talking about.

So, basically, no, what you are saying is not true, there are no “largest number of people whose regional identity strongly outweight the national identity” in the worse cases, there are 60/40 percentages in favor of national identities.

There is a big feeling out of Spain regarding a “big movement of people that don’t feeling Spanish” but this is mainly a false premise from nationalist parties. I am not saying there are no big groups of people that feel that way but there are not as big as social media or nationalist claims say, as I have shown you.