BARCELONA, Spain -- Voters in Catalonia on Sunday are choosing lawmakers for this wealthy Spanish region's parliament amid a threat from the Catalan leader to hold an independence referendum that would test the country's unity.

The regional government, led by Artur Mas, called early elections as part of a power struggle with the central government run by Prime Minister Mariano Rajoy centered on the size of Catalonia's contribution to national coffers.

If voters give Mas strong support on Sunday, he has pledged to hold a referendum asking Catalans if they would prefer to split from Spain at a time of deep financial crisis.

Rajoy has said that talk of independence is a side issue to the country's real problem, which is to find a way to create employment and address its deficit.

While Rajoy is immersed in combating Spain's worst financial crisis in decades, Mas claims Catalonia is being asked to shoulder too much of the tax burden and that it could do better if it separated and tried to become an independent member state of the European Union.

"Five years ago I was in favor of a federal model with Spain, but now we have seen that is not viable," said Miquel Angel Aragon, a 37-year-old aid worker. "I am in favor of independence."

Catalonia is responsible for around a fifth of Spain's economic output and many residents feel central government gives back too little in recognition of the region's contribution.

Madrid has traditionally said that simplifying the state's financial model by excluding overall costs such as defense only creates a distorted image of how taxation and spending are distributed.

A rising tide of Catalan separatist sentiment was spurred when Rajoy failed to agree to Mas' proposals to lighten Catalonia's tax load and hundreds of thousands of people turned out for a huge pro-independence rally in Barcelona on September 11.

The crisis has highlighted the high cost of running Spain's 17 semi-autonomous regions alongside a central government.

Catalans are viewed by most Spaniards as thrifty, hardworking people, and most have been shocked by how Catalonia's regional debt has swelled to (EURO)42 billion ($54.4 billion) of the staggering (EURO)140 billion debt ascribed to all of Spain's regional governments.

"We are not separatists, we want to remain part of Spain," said retired industrial designer Francisco Palau, 69, who emerged from a polling station alongside his wife. "We defend current plurality," he said, adding that setting up a new state and government "would be very expensive."

Just over 5.2 million people are eligible to vote for candidates to fill the 135-seat Catalan parliament that sits in Barcelona.