Spain’s deputy prime minister, Soraya Sáenz de Santamaría, will take over the Catalan administration from Madrid.
Dozens of other Catalan officials were expected to be fired, but Enric Millo, the current representative of the central government in Catalonia, told Catalunya Radio on Saturday that he expected Madrid to make “the minimum possible” staff changes.
Mr. Puigdemont, speaking from the Catalan capital, Barcelona, insisted that Mr. Rajoy was removing a democratically elected government.
“These are decisions contrary to the will expressed by the citizens of our country at the ballot boxes,” he said. He added that the central government in Madrid “knows perfectly well that, in a democratic society, it is the Parliaments that choose or remove presidents.”
Madrid also took control of the regional police force and fired the regional police chief, Maj. Josep Lluís Trapero.
So far, there is no indication that Catalan officials will resist their removal. Pere Soler, the ousted director general of the Catalan police force, sent a letter to his officers, expressing regret over his removal and thanking them for their work.
Major Trapero — who is facing possible sedition charges after he was accused of failing to stop protesters last month from encircling national police officers — also wrote to his colleagues. He reminded them that their task was to “guarantee the safety of everybody” in the coming days, should the political crisis spur more unrest.
As Mr. Puigdemont spoke on Saturday, throngs of Spaniards gathered in central Madrid — many of them waving flags, some wrapped in them — to protest Catalonia’s unilateral declaration of independence.
“We are resisting xenophobia,” one man said into a microphone, before shouting: “Long live Catalonia, long live the king, long live Spain.”
The crowd chanted: “Don’t fool us, Catalonia. You are part of Spain.”
Many protesters said that the Madrid government had to enforce its decision to trigger Article 155. Some said that, if necessary, the army should be sent in, though most said it would not come to that.
“They need to apply the law,” said Chema Martinez, 22, who described himself as a patriot and devout Catholic and wore a Spanish flag with the Sacred Heart of Jesus stamped on its center.
“The army is there to defend Spain,” he said. “They should send in the army to Catalonia; that’s what needs to be done.”
At one point, the Spanish national anthem began to play, and many who had been quietly listening as they sat on the curb silently stood up.
Agueda Rivera, 77, tears streaming down her face, said, “I’m crying. I’m crying for my Spain.”
On Friday, Mr. Rajoy announced that new Catalan elections would be held on Dec. 21, the earliest possible date, in an apparent bid to show frustrated Catalans that Madrid wanted to avoid prolonging a constitutional crisis.
By limiting Madrid’s control over Catalonia to 55 days, analysts said, Mr. Rajoy and his allies were hoping to quickly turn the tables on the separatists, who staged an independence referendum on Oct. 1 that had been declared illegal by Spain’s government and courts.
“It’s Rajoy’s attempt to regain the democratic initiative, but also a surprisingly risky bet that he can really beat the independence movement,” said Josep Ramoneda, a political columnist and philosopher.
“Whether it works will depend on the level of resistance to Madrid in the coming weeks, which perhaps won’t be that high given that people are exhausted and need a break.”
Albert Rivera, the national leader of Ciudadanos, the party that has been Mr. Rajoy’s main ally in fighting secessionism, told a party conference on Saturday morning, “We will now come out to beat them, but by voting.”
The December elections, he said, were an opportunity for “all the Catalans who have been silenced by nationalism,” after opponents of independence mostly boycotted the Oct. 1 referendum.
“We will now claim the right to vote in freedom,” Mr. Rivera added, “to show the world that this is a free and democratic country.”
Vicent Sanchis, the general manager of the Catalan public television station, TV3, said that it remained to be seen how much practical control Mr. Rajoy could exert over Catalan institutions.
“We live in an uncertain moment,” Mr. Sanchis said in his office. “We now have two parallel legitimacies and we still don’t know which one controls the Catalan institutions.”
“The key thing now is to discover what pressure the Madrid government will now exert,” he added. “In the coming days, we’ll find out.”
Jordi Borda, the deputy director of Catalunya Radio, said a crucial test would come on Monday.
“If the Catalan ministers go to work on Monday and manage to work normally, it will be a strong step towards consolidating what the Catalan parliament voted on yesterday,” Mr. Borda said.
“If Monday is a normal day,” he said, “it will be a victory for the independence movement.”
Spain’s attorney general is expected to take legal action against Mr. Puigdemont and other leading separatists on Monday, possibly on grounds of rebellion, which carries a prison sentence of as long as 30 years.
Joan Queralt, a professor of criminal law at the University of Barcelona, said he expected the attorney general to act forcefully.
“One thing is what the law says and another is how far the government can act,” Professor Queralt said. “I’ve got the feeling that the attorney general will do whatever he wants, just as happens when governments deal with terrorists.”