Voters in Spain head to the polls Sunday in a general election that is expected to turf the ruling Socialists in favour of the conservative Popular Party.

Polls suggest the Socialists are expected to lose in a landslide after eight years in power, a biting economic crisis and record unemployment that has taken its toll on Socialist candidate Alfredo Perez Rubalcaba.

Political parties finished campaigning at midnight local time on Friday, giving voters the traditional full day on Saturday to reflect before Sunday's balloting.

Thousands of Popular Party supporters filled Madrid's Sports Palace on Friday night for a final rally. Opinion polls have the party's candidate for prime minister, Mariano Rajoy, collecting nearly half the popular vote and ahead by 15 points over Rubalcaba.

Rajoy has promised to get Spain's economy working again to reduce the 21.5 per cent unemployment rate, but has been vague on details.

Debt risk

A near two-year recession has left the country with a euro-zone high unemployment figure and a swollen deficit. Spain's key borrowing rate remained above six per cent for a fifth day running on Friday — up roughly one per cent from last week, and in territory that makes it expensive for the government to service its debt.

"I come to this key moment hoping to be able to change things, with the ideal of being able to solve the great problems we have had in this country for many years, and with the resolve to give back to Spaniards their confidence in themselves, get them back their jobs and prosperity, ruined by years of poor management and bad government," Rajoy told supporters at the rally.

Rubalcaba, a former interior minister, says Rajoy plans to dismantle much of Spain's welfare state and cut back on worker rights to favour businesses.

Spain's outgoing Prime Minister Jose Luis Rodrigo Zapatero is not running for a third term.

Nearly 34 million people are registered to vote. They will cast ballots Sunday for 350 deputies in parliament's lower house and 208 senators.