The most serious threat to Spain's national unity in decades may come to a head Tuesday when the leader of Catalonia reveals whether he will make good on his promise to declare independence for the region during a speech.
Such a declaration, which follows an Oct. 1 independence referendum held over Spain's objections, would deepen the ongoing political crisis that has reopened old divisions in a nation where the right-wing dictatorship of General Francisco Franco, who died in 1975, still lingers.
Here is the status of the standoff between the affluent, industrial region of Catalonia and the central Spanish government in Madrid.
The leader of the autonomous region, Carles Puigdemont, was holding a meeting of his cabinet to decide how to press an independence drive that has stirred powerful emotions across Spain and raised concern in European Union partner states. Catalan police armed with automatic rifles stood guard at Barcelona's Parc de la Ciutadella which houses the parliament. Spanish national police, decried by separatists over their use of force to hinder the Oct. 1 referendum, were not to be seen.
The parliament and other buildings, such as the regional high court building, could become a focus of contention between Spanish and Catalan authorities.
Pro-independence demonstrators were due to gather before the parliament building under the slogan "Hello Republic" to mark Puigdemont's speech. Puigdemont has said he is determined to apply a law passed by the Catalan assembly which called for a declaration of independence within days if Catalans voted "yes" in the referendum.
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While the conflict over a self-determination vote has been dragging on for years, tensions ratcheted up when Catalan separatists staged the Oct. 1 vote despite Spain's insistence it was illegal.
Spanish police, ordered to prevent the referendum, clashed with voters and supporters, and Catalan officials said over 900 people were injured. Videos of police pulling voters out by their hair and kicking them on stairs flashed around the world.
Catalonian officials claim the referendum results give them a mandate to create a new country. But less than half of the region's electorate voted, and the way the referendum was held has raised a host of complaints about its legality and validity. As Spanish police started seizing ballot boxes, Catalan officials allowed voters to cast ballots wherever they liked.
Catalan officials say the final numbers show 90 percent of votes in favor of independence and Puigdemont proclaimed a victory. Spain cried foul and most governments backed Madrid. No one seems eager to recognize Catalonia, including the European Union.
Hundreds of thousands of people demonstrated in Barcelona against independence at the weekend, waving red-yellow Spanish flags through the city center.
Puigdemont could ask the parliament to vote on a motion of independence, which lawmakers say would start a period of up to six months during which Catalonia would write a new constitution and negotiate a divorce with Spain. He could also make a statement of intent on a future independence declaration.
It's not clear what might happen if Catalonia does actually try to secede. Spanish Prime Minister Mariano Rajoy has vowed that Spain will not be divided and says he will use any lawful measure to stop the separatists. He said this includes the use of Article 155 of the Spanish Constitution, which would allow the central government to take control of the governance of a region "if the regional government does not comply with the obligations of the Constitution."
Ruling party lawmakers say Rajoy is considering taking the unprecedented step of dissolving the Catalan parliament and triggering new regional elections, the so-called nuclear option.
A split raises dozens of questions with no answers yet. Key issues include national boundaries with the rest of Spain and France, as well as its relationship with the EU. It's unclear how Catalonia can gain control of its defense and foreign affairs, tax collection and management of airports, ports, rail transport and nuclear stations, most of which are currently managed by Spain.
Losing Catalonia, which has its own language and culture, would deprive Spain of a fifth of its economic output and more than a quarter of exports.
The European Union has already said Catalonia would be expelled from the bloc and its shared currency, the euro, if it declares independence. To get back in, it would have to re-apply — a lengthy and uncertain process.