The agreement sent shock waves across the country, with Sánchez’s conservative opponents accusing him of compromising the rule of law for his own political gain.
“We will not remain silent until there are new elections,” said the leader of the Popular Party (PP), Alberto Núñez Feijóo, to a crowd packed at Madrid’s Puerta del Sol.
According to the authorities, 80,000 people gathered in Madrid, while the PP, which had called for demonstrations in cities throughout Spain, put the figure at around one million.
Many carried Spanish and EU flags, as well as banners with slogans such as “respect the Constitution.”
“Sánchez has betrayed coexistence, democracy… he cannot continue governing,” said banker Tomás Pérez, 38, holding a banner that read “Sánchez traitor.”
“Many people I know who vote for the Socialists feel absolutely disappointed because… Sánchez never said that amnesty would be part of his program,” said Inmaculada Herranz Castro, 64.
In Barcelona, local police said about 6,000 protesters gathered, while in Granada there were 30,000 and in Seville 50,000, according to authorities. Other protests took place in cities such as Malaga, Palma and Valencia.
Following an inconclusive July 23 election, the Socialists spent weeks negotiating with smaller parties, including the far-left Sumar platform and Catalan, Galician and Basque nationalist parties.
The confirmed support of Junts, as well as the Basque Nationalist Party, last week, would give Sánchez the absolute majority in the 350-member lower house, in a vote scheduled for the coming days.