The fragile coalition of Prime Minister Pedro Sánchez of Spain revealed deep and potentially paralyzing cracks on Tuesday when a tiny, hard-line Catalan separatist party he has allied with rejected a critical amnesty measure as unsatisfactory.
The party, Together for Catalonia, provided the support that allowed Mr. Sánchez to form the government last year, on the condition that he give amnesty for alleged crimes linked to the 2017 failed bid for independence. On Tuesday, the party argued that the legislative shield against prosecution for it and its leaders needed to be broader.
The voting down of the measure in Spain’s lower house was a setback for Mr. Sánchez, creating the likelihood of more weeks of arduous negotiations. It also raised the prospect that haggling over the amnesty deal — the very thing that gave birth to his second term in office — might render the government unable to pass basic legislation, including an upcoming budget.
“The problem is that this could be a zombie government,” said Pablo Simón, a political scientist at Carlos III University in Madrid, who added that since Mr. Sánchez had no incentive to call for early elections, the government could simply march along for months or years doing nothing if it didn’t untie the amnesty knot.
“This is revealing that the party support of this government is really weak,” he added.
The Together for Catalonia party, a pro-independence movement, has the ability to hold Mr. Sánchez and his government hostage over the issue because its few votes are required to pass legislation in a deeply divided, and polarized, Parliament.
The party itself is divided, making it harder to negotiate with, but it is seeking a blanket amnesty for Carles Puigdemont, the former regional president of Catalonia who led the failed secessionist movement in 2017 and who is still living in self-imposed exile in Belgium.
The party argues that amnesty has to be immediately applicable to ongoing cases and broader in order to protect against charges such as terrorism and treason. That is necessary, it says, to defend party members against a judiciary that they see as politically motivated and hostile.
A judge is investigating whether Mr. Puigdemont ordered the blocking of Barcelona’s airport and whether that amounted to terrorism. Another judge is exploring potential links between Mr. Puigdemont’s top advisers and Russia, suggesting it could be treason.
Mr. Sánchez, who cobbled his coalition together with a hodgepodge of parliamentary parties despite winning fewer votes than the country’s leading conservative party in last year’s elections, had sought to make concessions, but they were not enough. He and his allies worry that an overly broad amnesty may violate the Spanish Constitution or European Union law.
Conservatives warned that the amnesty agreement that brought Mr. Sánchez back to power amounted to a deal with the devil because it would give Mr. Puigdemont leverage over the entire government.
The amnesty bill was politically necessary for Mr. Sánchez, but publicly unpopular. Polls showed that a large majority of Spanish voters opposed it. The conservative opposition has in recent months organized mass demonstrations, attended by hundreds of thousands of people, to protest what they considered a deeply cynical miscarriage of justice.
Analysts expected that the fragmented nature of the governing coalition would cause problems for major legislative items like the upcoming budget or questions of autonomy and taxes for the northern regions. But the splintering is occurring earlier, and is sharper, than expected.
The amnesty measure’s defeat may be temporary, however. It will now head back to a commission to hammer out a new proposal, with potentially new amendments, and to be voted on again in no more than a month’s time.
But Mr. Sànchez and his socialists look weaker for the initial loss.
“This government is having problems since the very beginning — it’s going to be difficult to rule,” said Mr. Simón, the political scientist. He added that the government and its allies worried that this “is going to happen on each single vote.”