The Socialist prime minister won a parliamentary vote only after promising amnesty to Catalan separatists, enraging conservatives.Pedro Sánchez, the Spanish progressive leader, secured a second term as prime minister on Thursday after a polarizing agreement granting amnesty to Catalan separatists gave him enough support in Parliament to govern with a fragile coalition over an increasingly divided nation.With 179 votes, barely more than the 176 usually required to govern, Mr. Sánchez, who has been prime minister since 2018, won a chance to extend the progressive agenda, often successful economic policies and pro-European Union posture of his Socialist Party.The outcome was the result of months of haggling since an inconclusive July election in which neither the conservative Popular Party, which came in first, or the Socialist Party, which came in second, secured enough support to govern alone.But the fractures in Spain were less about left versus right and more about the country’s very geographic integrity and identity. Mr. Sánchez’s proposed amnesties have breathed new life into a secession issue that last emerged in 2017, when separatists held an illegal referendum over independence in the prosperous northeastern region of Catalonia.That standoff caused perhaps the worst constitutional crisis for Spain since it became a democracy after the fall of the Franco dictatorship in the 1970s.It has since fueled a Spanish nationalist movement once considered taboo in the wake of Franco’s rule.Even before Mr. Sánchez could be sworn in, the prospect of an amnesty brought hundreds of thousands of conservatives and right-wing hard-liners into the streets in sometimes violent protests that have also drawn the American rabble-rouser Tucker Carlson. Spain’s courts have criticized the proposed amnesty as a violation of the separation of powers. European Union officials are watching nervously.Demonstrators gathered in Barcelona, Spain, on Sunday, to protest the government’s proposed law that would grant amnesty to Catalan separatists.Pau Barrena/Agence France-Presse — Getty ImagesThe parliamentary debate leading to Thursday’s vote in a building protected by barricades was particularly bitter as Mr. Sánchez defended the proposed clemency law from conservative accusations of corruption and democratic illegitimacy.“Every time the national dimension enters the arena, emotions grow and the debate is even further polarized,” said José Ignacio Torreblanca, a Spain expert at the European Council on Foreign Relations, a think tank. Spain was in for “ugly, nasty and dirty” months ahead, he said.The separatism issue has given a “second life” to Carles Puigdemont, former president of the Catalonia region who was the force behind the 2017 secession movement and is now a fugitive in self-exile in Belgium, Mr. Torreblanca said. The hard-right party Vox, which, after a lackluster showing in the elections, has again raised its voice, calling for constant street protests.This seemed very much the situation Spaniards hoped to avoid when they cast most of their votes with mainstream parties in July, signaling that they wanted the stability of a strong center.In the balloting, the Popular Party persuaded many to choose their more mainstream conservatism over Vox but came up short of enough votes to form a government.Mr. Sánchez needed the support of a separatist party to govern — and in return offered amnesties, something he had previously called a red line he would not cross. The alternative was new elections.“The left face a great cost if they go to new elections, so having a government is crucial for them. But pro-independence parties face an important opportunity cost if this government is not in place,” said Pablo Simón, a political scientist at Carlos III University in Madrid. “All of them are very weak, but they need each other.”Carles Puigdemont, who has been in exile in Belgium, speaking by video link at a gathering of his Junts per Catalunya party in 2020.Quique Garcia/EPA, via ShutterstockPolls show that about two-thirds of Spaniards oppose the amnesty, demonstrated by large, and largely peaceful, protests throughout the country, though Vox politicians have attended violent rallies peppered with extremists outside Socialist Party headquarters. This week, Mr. Carlson, the former Fox News celebrity, attended one of the protests in Madrid with the Vox leader, Santiago Abascal, and said anyone willing “to end democracy is a tyrant, is a dictator. And this is happening in the middle of Europe.”Mr. Sánchez and his supporters have pointed out that their coalition — however much the hard right dislikes it — won enough support to govern, as the Constitution dictates. In a lengthy speech on Wednesday, Mr. Sánchez derided the conservatives for their alliance with Vox. He argued that the deal with the Catalan Republican Left and with the more radical Junts per Catalunya, the de facto leader of which is Mr. Puigdemont, was required to promote unity for the country.“And how do we guarantee that unity? You can try the path of tension and imposition, or you can try the path of dialogue, understanding and forgiveness,” Mr. Sánchez said, citing his record of pardoning imprisoned separatist leaders in 2021 as a way to reduce tensions with Catalonia. He said that the conservative hard-line approach had brought the unsuccessful 2017 move for secession in the first place.The conservative Popular Party’s leader, Alberto Núñez Feijóo, attacked Mr. Sánchez as “the problem.”“You and your inability to keep your word, your lack of moral limits, your pathological ambition,” he said. “As long as you’re around, Spain will be condemned to division. Your time as prime minister will be marked by Puigdemont returning freely to Catalonia. History will have no amnesty for you.”The leader of the conservative Popular Party, Alberto Núñez Feijóo, center, at a protest against the amnesty bill in Madrid on Sunday.Thomas Coex/Agence France-Presse — Getty ImagesBut Mr. Sánchez seemed unaffected and instead mocked the conservatives as having a record of corruption and for being motivated by sour grapes over losing the election, laughing at Mr. Feijóo, who sat in front of him.“I don’t understand why you’re so keen to hold a new election if you won the last one,” Mr. Sánchez said.Mr. Sánchez also took direct aim at the leader of Vox, Mr. Abascal, saying, “The only effective barrier to the policies of the far right is our coalition government.”The amnesty bill would cancel “penal, administrative and financial” penalties against more than 300 people involved in the independence movement from Jan. 1, 2012, to Nov. 13, 2023.But Mr. Sánchez’s Socialists had also agreed to relieve millions of euros in debt to Catalonia, a demand of the separatists, and to give it some control over commuter train services. Mr. Puigdemont’s party had demanded that Catalonia, which is a wealthy region, keep more of its tax revenues, and that referendum talks should restart, though this time abiding by the demands of the Spanish Constitution.Conservatives have vowed to fight the law, which will take many months to work its way through Parliament and must overcome serious hurdles, not least of them the objection of Spanish judges. There is the risk that if the separatists are stymied by the courts, which they consider politically motivated, they could drop out of the coalition, essentially paralyzing Mr. Sánchez’s legislative agenda.“Probably this government will be stuck in Parliament,” said Mr. Simón, the political scientist, adding that grievances over the amnesties in regional governments controlled by conservatives would hurt cooperation and governance as well.There is also the question of whether Mr. Puigdemont could once again pursue an illegal referendum, recreating the trauma of 2017. That would probably embolden the nationalist Vox, whose grave warnings about the destruction of Spain would seem legitimized.“If you activate this extinction or survival mode of Spanish nationalists, then the conservative party may not be the best option because you are frustrated and angry,” said Mr. Torreblanca, the analyst.He added that Spain could be entering a risky scenario in which “those who lose the elections do not accept that they have lost, not so much because the vote was rigged, but because the government is doing things which they considered outrageous.” More