Catalan president Artur Mas's party will fall short of the overall majority it needs at regional elections on 25 November to hold a referendum over Catalonia's independence from Spain, opinion polls published in several Spanish newspapers on Sunday have predicted.

A survey by the Metroscopia polling group in El País, Spain's biggest selling non-sports paper, predicted Convergència i Unió's (CiU) haul would be unchanged at 62 seats in the 135-member Catalan parliament after next Sunday's polls. Meanwhile, Barcelona-based daily La Vanguardia forecast the conservative party would garner 62-64 legislators in the assembly, compared with the 68 they would need to govern without the support of six other parties expected to win seats.

Mas, who has led a minority government for two years, called for early elections and a referendum after an independence rally in the regional capital Barcelona on 11 September drew an estimated 1.5 million people, equivalent to about one in five of the north-eastern region's inhabitants.

A recent survey by Catalan government-funded research group CEO predicts 57% of Catalans would vote to break away from Spain. However, the central government has said a referendum in the rich but indebted region would be unconstitutional, and the constitutional court in Madrid blocked a move to hold a similar vote in the northern Basque country as recently as 2008.

Another potential stumbling block for a separation has been raised by doubts over whether an independent Catalonia could remain in the European Union. When asked on Saturday at the Iberoamerican summit held in Cádiz, European commission president José Manuel Barroso replied that the bloc would stand by rules drawn up in 2004, ie states that secede would have to apply for membership.

"The legal situation has not changed since 2004. The Lisbon treaty has not introduced any modifications in that respect," he said.

Catalonia has a distinct language and culture and, like all of Spain's 17 regions, enjoys considerable autonomy, but the CiU is demanding the right to collect its own taxes and send a share to Madrid, an arrangement similar to the Basque country.

Less at the forefront of the campaign has been the deep spending cuts which have sparked massive protests across crisis-hit Spain. Mas's government had to ask Madrid for a €5bn bailout in August for Catalonia, which is Spain's wealthiest region and accounts for 18.5% of Spain's total economic output, but also for 29% of all outstanding debt held by the country's regions.