The leader of Spain's Catalonia region is due to address members of the regional parliament Tuesday, while the government in Madrid worries Catalan representatives will vote for a unilateral declaration of independence.
Catalan leader Carles Puigdemont did not reveal ahead of time what his message would be Tuesday.
Political leaders, both domestically and internationally, urged Catalan leaders on Monday to back down to ease growing tensions in the country.
Barcelona's mayor was the latest to speak out against a declaration of independence, saying it would put "social cohesion" at risk. Ada Colau called on all sides to de-escalate tensions to solve "the most severe institutional crisis since the re-establishment of democracy in Spain."
The head of Spain's main opposition party, Socialist leader Pedro Sanchez, also called for Catalan leaders to drop an attempt to declare independence, saying "a universal declaration of independence doesn't have a place in a state ruled by law."
Germany and France also weighed in Monday against a split. German Chancellor Angela Merkel "affirmed her backing for the unity of Spain," but also encouraged dialogue, according to her spokesman.
France said it would not recognize Catalonia if the region declared independence. "This crisis needs to be resolved through dialogue at all levels of Spanish politics," France's European Affairs minister, Nathalie Loiseau, said.