MADRID (Reuters) - Catalonia’s pro-independence parties agreed on Saturday on a new leader, clearing the way for the creation of a regional government and raising pressure on national parties in Madrid to form a broad coalition to oppose the separatist drive.

Catalan acting President Artur Mas gestures during a news conference at Palau de la Generalitat in Barcelona, Spain, January 5, 2016. REUTERS/Albert Gea

The parties’ agreement to back Carles Puigdemont, a fiery separatist, in a vote due on Sunday came after the region’s acting head, Artur Mas, said he would step down in an attempt to break months of political deadlock in Spain’s wealthiest region.

The move, which comes three weeks after an inconclusive national election, increases pressure on acting Prime Minister Mariano Rajoy and his Socialist rivals to bury their differences and form a German-style “grand coalition” in Madrid to thwart the Catalan parties’ push for independence within 18 months.

Catalonia’s politicians have been unable to form a government since a September regional election due to disagreements between the pro-independence parties that together hold a majority in the Barcelona assembly.

A minority leftist party in the pro-independence bloc, CUP, had opposed Mas’s bid for another term due to deep differences over such issues as an independent Catalonia’s membership of NATO and the European Union. Mas has led the region since 2010.

Mas said on Saturday he backed Puigdemont as his successor. El Pais newspaper has quoted Puigdemont as saying in a 2013 speech that he would “chase the invaders out of Catalonia” - a swipe at the central government in Madrid.

A majority of people in Catalonia, a region of 7.5 million people with its own distinct language and culture, say they want to remain part of Spain but with greater autonomy on issues such as tax, opinion polls show.

Catalonia accounts for almost a fifth of Spanish economic output.

APPEAL FOR STABILITY

Rajoy’s center-right People’s Party (PP), which won the most votes but fell well short of a majority in the Dec. 20 national election, renewed its appeal on Saturday for a broad-based government in Madrid to avert the country’s fragmentation.

“The next government of Spain should have a broad parliamentary base that guarantees stability and the capacity of the state to reliably defend the right of all Spaniards to determine their country and confront the separatist challenge,” the PP caretaker government said in a statement.

Rajoy has asked the Socialists to join a coalition that could also include centrist newcomers Ciudadanos, but Socialist leader Pedro Sanchez has roundly rejected the overtures.

Sanchez wants to form a coalition of ‘progressive forces’, but a major sticking point is the election promise of leftist newcomer party Podemos to allow an independence referendum to go ahead in Catalonia.

The PP government refused to allow a referendum in Catalonia in 2014, arguing it would contravene Spain’s constitution.

Catalonia’s parties have to agree on a new leader by a Jan. 11 deadline or new regional elections must be held.

Mas said on Saturday that would be the worst option for Catalonia, comments that suggest the pro-independence movement has started to lose steam since its peak at the height of Spain’s economic crisis when it drew one million people onto the streets of Barcelona to demand a split from Spain.