No sooner had Pedro Sánchez arrived at Barcelona’s Liceu opera house to announce the pardons of nine Catalan separatists than the obstacles to his attempt at defusing Spain’s most divisive political dispute became clear.

Supporters of Catalonia’s independence barracked the socialist prime minister. The leaders of the region’s separatist administration refused to attend his speech, calling for a broader amnesty and an independence referendum. Meanwhile in Madrid, the central government’s capital, rightwing politicians called him a “traitor” who had caved in to “coup plotters”.

And yet Sánchez’s political gamble — which has received backing from figures in business and the Catholic church — could be a rare chance to make progress on Spain’s biggest unresolved issue, some analysts suggest.

“This is the best opportunity on the Catalan dispute for at least a decade,” said Oriol Bartomeus, a political scientist at the Autonomous University of Barcelona.

Both the national and regional governments are now led by parties vowing to seek dialogue rather than confrontation, he noted, adding that Sánchez’s move unlocked “a way forward towards dialogue, but the forces that are ranged against it are very strong”.

Sánchez’s government argues the pardons can suck the poison from the Catalan dispute, which has rocked Spanish politics for more than a decade and left the region itself in stasis, with a pro-independence administration and a population almost evenly divided between separatists and unionists.

That state of affairs has complicated the formation of any stable government in Madrid — partly because of the swing votes of separatist MPs — and led to an illegal secessionist referendum in 2017. That in turn sparked off an abortive unilateral declaration of independence, as well as the prison sentences for the nine politicians and activists whom Sánchez’s government partially pardoned on Tuesday.

Sánchez argued that his move was necessary to shift the dispute from the legal to the political realm, noting that “millions of Catalans feel an emotional link with the imprisoned leaders”.

The pardoned prisoners include Oriol Junqueras, who leads the party that heads the regional administration, the Catalan Republican Left or ERC — which also frequently helps the prime minister win votes in the national parliament. But if Sánchez’s gambit does not bear fruit, he and his minority government will be weakened.

Success is anything but guaranteed, according to Astrid Barrio, an academic at Valencia university, who highlights three fronts where Sánchez’s efforts could be undone: the political, the judicial, and the bureaucratic.

According to one poll, opponents of the pardons outnumber supporters two to one — and the centre-right People’s party is challenging them in court.

Furthermore, many militants — both separatists and unionists — reject the dialogue Sánchez is hoping to initiate: some two years of talks that could end with a deal on enhanced autonomy.

The most important response may come from the ERC, which Sánchez’s Socialists — a fellow left-of-centre party — see as a promising interlocutor.

But the reaction this week of Pere Aragonès, the ERC politician who heads the Catalan government, was less than effusive: he described the pardons as “inadequate and incomplete”. He added: “The repression against Catalan citizens goes much further” — a reference to Spanish judicial and administrative actions.

Spain is still seeking the extradition of exiled separatist leaders involved in the 2017 referendum, most notably Carles Puigdemont, the leader of the regional administration at the time who now lives in Belgium. Court cases are continuing against dozens of lower level figures involved in the 2017 events.

On the administrative front, Spain’s court of auditors is set next week to demand that about 40 former Catalan officials repay millions of euros in regional government funds it says were wrongly used to promote independence — and to seize assets if they do not comply.

Among those facing such a prospect is Andreu Mas-Colell, a former Harvard economics professor who on Tuesday received the support of 33 Nobel laureates.

The dispute has made waves abroad: on Monday the parliamentary assembly of the Council of Europe bracketed Spain with Turkey, calling for an end to prosecutions and signalling its concern with the court of auditors’ actions.

Spain’s government accused the assembly of turning a blind eye to the country’s fundamental separation of powers. But it is already proceeding on one of the council’s main recommendations: revising the law on sedition, the offence for which the nine prisoners were found guilty.

Generally, Sanchez’s government has argued there is no alternative to negotiations for a country and region that has grown weary of conflict.

Business figures make a similar argument after years in which Catalonia’s instability helped Madrid edge ahead of it as the biggest contributor to Spain’s gross domestic product, as thousands of companies moved their headquarters out of the region.

“The resolution of the conflict could be 10 years off, but the dispute is now no longer so inflamed and greater political stability has a considerable economic value,” said Javier Faus, a Spanish private equity investor and head of the Cercle d’Economia, a Catalan business-oriented think-tank.

“You can already see it,” he added. “After three-and-a-half years, the money markets, the institutions, have discounted the possibility that independence is going to happen; they understand that Catalonia is not going to leave Spain.”