Prime Minister Pedro Sánchez offered the amnesty in order to shore up support needed to form a new government in a deeply politically divided country.

But the gambit has sparked anger on the right, which sees dangling the possibility of an amnesty for those behind the secession attempt, which sparked a huge political crisis, as an assault on the rule of law.

Marchers gathered in 52 major cities across the country to show opposition to the plan, at the behest of the conservative main opposition Popular Party and its allies.

“We shall not remain silent until there are new elections,” vowed PP leader Alberto Núñez Feijóo in a speech in Madrid.

Feijóo’s party came first in July’s legislative elections but was unable to obtain a workable majority in parliament.

After Feijóo failed to cobble together a majority, it fell to Sánchez to try to form his own. He looks set to succeed with the amnesty offer.

Feijóo said Sunday’s mobilisation was for an issue which goes “far beyond party” as some 80,000 people turned out in the capital, according to the city prefecture, amid a sea of red and yellow Spanish flags around Puerta del Sol square.

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Marchers bellowed “Pedro Sánchez resign,” and held up banners urging an “end to regional inequality” and “Sánchez, you are breaking up the nation”.

Behind their backs

Catalan support Sánchez is set to retain power in parliament next week thanks to the votes of legislators from the party of Carles Puigdemont, the main face of the independence campaign at the time of the referendum who afterwards, pursued by Spanish justice, fled into Belgian exile.

The amnesty offer and a readiness to open talks on the future of Catalonia has won Sánchez the support of Puigdemont’s Junts (Together) party in exchange.

But the right is incandescent and parts of the judiciary as well. Some strands of Sánchez’s own Socialists are also opposed seeing the amnesty as trampling on constitutional values such as equality for all Spain’s regions and the separation of powers.

Draped in a Spanish flag at the Madrid rally, lawyer Laura Díaz Bordonado said she feels not only “anger and indignation, but also fear” at the alliance between the government and the separatists.

Alberto, a 32-year-old teacher, who also votes conservative, meanwhile denounced a pact which he said had been done “behind the backs” of Spaniards.

‘Coup d’etat’

On Saturday, Sánchez, who has been in office since 2018, in an address to a congress of European socialist groups in Malaga, southern Spain, urged the PP “to accept the ballot result and the legitimacy of the government we are soon going to form.”

Latest polls Friday showed support for his Socialist Party (PSOE) has dropped 1.3 percentage points in a month, falling to 31.3 percent, while the PP gained 1.7 points to 33.9 percent.

Far-right party Vox joined Sunday’s rallies while also demonstrating outside PSOE offices countrywide.

In Madrid, Vox leader Santiago Abascal called for a “permanent” and “growing” mobilisation to avoid a “coup d’etat” which he said was what the deal between the government and the separatists amounted to.

The Socialists’ Madrid headquarters has in the past week been the scene of daily rallies called by groups close to Vox. Some have ended in violent clashes between radical elements and the police.