Spanish Prime Minister Mariano Rajoy urged Catalans on Sunday, 12 December, to oust separatists from their regional parliament in an early election he has called for 21 December.
Rajoy told members of his conservative Popular Party in Barcelona that "we want a massive turnout to open up a new period of normalcy."
Rajoy's visit to Catalonia's main city was his first to the northeastern region since he used extraordinary powers to stifle its secession push.
After Catalonia's Parliament voted 27 October in favour of declaring independence, Rajoy responded by firing its government, dissolving its parliament and calling the early election.
Spain's Constitution says the nation is "indivisible."
"It's urgent to return a sense of normality to Catalonia and do so as soon as possible to lower the social and economic tensions," Rajoy said on Sunday.
"The threat of the separatists is destructive, sad and agonising. Secessionism has created insecurity and uncertainty."
Polls show a tight race ahead in Catalonia between separatists and those who want the region to remain a part of Spain.
In Brussels on Sunday, those favouring independence for Catalonia rallied near the European Union quarter.
Rajoy's conservative Popular Party has won three national elections in Spain since 2011, but it won less than 10% of the vote in Catalonia's regional election in 2015. It continues to poll behind several other parties in the region, including the pro-business Citizens and the Socialists, which are both against secession.
Rajoy defended his decision to temporarily take over running the region under the Constitution, which allows central authorities to intervene in regions whose officials have gone outside the law.
Catalonia's separatists, and even some moderates, have criticised the measures as heavy-handed.
"Exceptional measures can only be taken when there is no other option, and we adopted them to stop the increasing attacks to peaceful coexistence" in Catalonia, Rajoy said.
"For centuries, centuries, Catalonia and Spain have built a country that is multi-cultural and diverse, and the separatists won't be allowed to break the ties that bind us."
Apart from the Catalonia government takeover, a judge has jailed 10 separatist leaders while investigating their roles in promoting secession.
Catalonia's deposed president and four former members of his Cabinet have fled to Brussels where they will fight extradition.
Rajoy linked the continued economic recovery of Spain, and especially Catalonia, to the removal of pro-independence parties from power.
Over 2,000 companies have relocated their headquarters from Catalonia due to fears of being cast out of the European Union's common market in the case of secession.
Employment numbers also showed that Catalonia fell behind other parts of Spain in October.
"The instability is slowing Catalonia's capacity to create jobs," Rajoy said. "But I say that the recovery of legality and normalcy will help reactivate the economy."