Updated at 5:25 a.m. ET
Catalan President Carles Puigdemont, in a letter on Monday to Spain's prime minister, called for more dialogue over the status of the semi-autonomous region, but he failed to meet a demand from Madrid to clarify a declaration of independence or face direct rule.
Spain's Prime Minister Mariano Rajoy imposed a deadline last week for Puigdemont to give a yes or no answer on the question of independence, saying a yes or ambiguous answer would force Madrid to suspend Catalonia's autonomy and impose direct rule.
In response to letter, Spain's Deputy Prime Minister Soraya Sáenz de Santamaría said Puigdemont had until Thursday to comply with the country's laws.
In an address to reporters, she said "it wasn't very difficult to say yes or no. That was the question that was asked and the response shouldn't be complicated."
She said if Puigdemont doesn't give a satisfactory reply by Thursday morning, Spain could activate Article 155 of the Constitution, allowing it to strip Catalonia of its self-governance.
Last week, following an Oct. 1 referendum that went for Catalonia to break away from Spain, Puigdemont declared independence for the region of 7.5 million people, including the city of Barcelona. However, he quickly withdrew the declaration, calling instead for talks with Madrid on the region's future.
Even so, Puigdemont and other Catalan lawmakers signed a document declaring a Catalan republic "as an independent and sovereign state."
The declaration angered Spanish authorities, who had called the referendum illegal and tried to stop it.
As NPR's Lauren Frayer wrote on Friday, the answer "has huge implications for what the Spanish government does next and how the country's relatively young democracy — indeed, possibly even the whole European Union — might stay intact."
The government of Catalonia says 90 percent cast a "yes" ballot on the independence referendum, but most people who opposed breaking away from Spain boycotted the vote. Opinion on the issue is reportedly nearly evenly split and turnout for the referendum was just 43 percent.