The Spanish government is set to hold a special cabinet meeting to approve measures to take direct control over Catalonia.
The meeting comes almost three weeks after the region held an independence referendum, which was ruled illegal by the country’s supreme court.
Catalan leader Carles Puigdemont has refused to abandon independence, arguing that he has a mandate.
Spain’s central government is now preparing to take back power.
The government is expected to trigger Article 155 of the constitution, which allows it to impose direct rule in a crisis. It has never before been invoked in democratic Spain.
Catalonia has a population of about 7.5 million and currently enjoys significant autonomy from Spain, including control over its own policing, education and healthcare.
On Saturday, the Spanish cabinet will discuss dissolving the region’s government and holding elections in January, as well as other measures including taking control of the regional police force.
Prime Minister Mariano Rajoy said the measures were aimed at restoring the rule of law and had been agreed with Spain’s opposition parties.
The steps will then be debated by a Senate committee before a final vote. Mr Rajoy’s conservative Popular Party (PP) holds a majority in the Senate, meaning the proposals are likely to pass.
Catalonian authorities are seeking full independence from Spain. The country has been in crisis since a disputed referendum was held in the region on 1 October.
Of the 43% of Catalans said to have voted, 90% were in favour of independence. But many anti-independence supporters boycotted the ballot, arguing it was not valid.
Mr Puigdemont and other regional leaders then signed a declaration of independence, but immediately suspended it in order to allow for talks.
Madrid responded by demanding to know whether or not Catalonia had declared independence, setting two deadlines for Mr Puigdemont to provide an answer.
Both deadlines passed with no response, and the Spanish government now insists it must intervene in the region to uphold the rule of law.
However, this leaves Mr Rajoy in a delicate position, says the BBC’s Tom Burridge in Zaragoza, Catalonia.
Any move, like taking control over Catalonia’s regional police force, action against Catalonia’s public TV channel or replacing Catalan officials with people loyal to Madrid has the potential to backfire, he said.
Spain’s King Felipe VI said on Friday that Catalonia was pursuing an “unacceptable secession attempt” and called for the crisis to be resolved “through legitimate democratic institutions”.
“We do not want to give up that which we have built together,” he said.