FACTBOX: Main issues in Spain's parliamentary election

(Reuters) - Spain is holding a parliamentary election on Sunday. Opinion polls show the ruling Socialist party of Prime Minister Jose Luis Rodriguez Zapatero leading the opposition conservative Popular Party (PP).

Following is an overview of how the parties plan to tackle the key issues that could decide the vote in the eurozone's fourth biggest economy, where 45 million people live.

SLOWING ECONOMY

The economy was previously one of the government's strongest cards thanks to record low unemployment and to growth rates that took Spain past Italy in per capita purchasing power.

A global credit squeeze on an already cooling property market could push economic growth down from 3.8 percent last year to near 2.0 percent this year, economists say. Consumer confidence has been at all-time lows in the last few months, although it rebounded in February.

With household debt at 130 percent of annual income and interest rates rising, many people are already struggling to meet mortgage repayments. Spaniards are also complaining about racing food and fuel prices, which pushed inflation to 4.4 percent in February.

IMMIGRATION

The number of foreigners registered as living in Spain has grown from under 1 million people in 2000 to over 4 million today, or 9 percent of the population -- most of them from Morocco, Eastern Europe and Latin America.

Popular Party leader Mariano Rajoy has linked immigrants to rising crime and blamed them for strains on the welfare state. He also wants restrictions on Muslim headscarves. Under a PP government, foreign immigrants would have to sign a contract promising to adopt Spanish customs.