After socialist PM’s attempt to calm tensions with Catalonia, right wingers call him a traitor and demand elections.

Madrid, Spain – Tens of thousands of Spaniards descended on Madrid to call for the end of the Socialist-led minority government and demanded that Catalan separatist leaders be put in prison.

The demonstration on Sunday, called by a coalition of three right-wing parties – the People’s Party (PP), Citizens and the VOX – draped Madrid’s Plaza De Colon in Spanish flags as protesters chanted slogans like “Long Live Spain!” and “Long Live the Police!”

The Spanish government estimated the number of demonstrators at 45,000, while organisers said 200,000 attended. Many held signs saying “Stop Sanchez”, a reference to Spanish Prime Minister Pedro Sanchez, who has overseen talks with Catalan separatists in recent months.

“Spain’s sovereignty isn’t a negotiation,” Marcos Villalobos, a student at Madrid’s Complutense University, told Al Jazeera at the protest. “We are one country.”

Many right-leaning Spaniards are alarmed by the willingness of the Spanish Socialist Party (PSOE) to negotiate with Catalan nationalist parties on regional self-determination before the high-profile trial of 12 Catalan leaders accused of rebellion, embezzlement and disobedience in relation to Catalonia‘s failed 2017 independence bid.

Sanchez said he “respected” the demonstrators during a speech in the north of Spain, but said the PSOE-led government would continue supporting “coexistence, law and dialogue in Catalonia”.

PSOE holds 84 seats in Spain’s 350-seat Congress of Deputies, roughly half the number needed for a majority.

The centre-left party has a tenuous alliance with a left-wing coalition headed by Podemos that holds 67 seats, which means the group requires support from smaller Catalan and Basque nationalist parties.

Sanchez is currently trying to pass a national budget to prevent new elections. The two major Catalan nationalist parties, the Republican Left of Catalonia and the Catalan European Democratic Party, announced they would not vote for the budget this week.

As a result, Sanchez is now fighting to save his government.

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As demonstrators sang pro-Spain songs in Plaza de Colon, Marta Feijoo, a pensioner from Galicia in Spain’s north, said Spain’s political situation wasn’t a matter of negotiations, but of law.

“The Catalan leaders broke the law. They have no respect for the Constitution. Politics isn’t about changing the law, but respecting it,” she said.

Sebastian Balfour, an emeritus professor of history at the London School of Economics who specialises in modern Spain, told Al Jazeera that Catalan nationalist parties have never held such sway over the national government.

“The situation is unprecedented,” Balfour said.

Spain’s Supreme Court starts its trial on Tuesday for the 12 leaders of the Catalan separatists.