The front-runner to be Spain's new prime minister, Mariano Rajoy, has pledged to restore confidence to the troubled economy and boost business.
Opinion polls ahead of Sunday's election show the People's Party, led by Mr Rajoy, has a double-digit lead over the Socialists.
The Socialists are widely seen by Spaniards as having mishandled the response to the mounting eurozone debt crisis, and are blamed for economic stagnation and an unemployment rate of 21.5%.
Spain will become the latest precarious eurozone country to replace its leadership, following Greece, Ireland, Italy and Portugal.
Economic woes have dominated the campaign, with more than one in five workers out of a job, a recession looming and government borrowing costs soaring to levels that forced other eurozone countries to resort to international bailout funds.
The new prime minister will not be sworn in until around 20 December.
Mr Rajoy has pleaded with markets to give Sunday's election winner "more than half an hour" to confront the economic crisis.
He is expected to try to calm financial markets by laying out the details of how he will shrink the public deficit and reform the economy to make it more competitive in the medium term.
However, the new prime minister will have little time to act. Spain sold a 10-year government bond yesterday with a yield of almost 7%. That high a borrowing cost has forced other countries into seeking international aid.
However, investor concerns over European government debt have shifted to Italy and France, which means that unless the euro common currency area comes up with a big picture solution, Mr Rajoy may not be able to save Spain from a fiscal meltdown.
Last night, thousands of teachers and students marched in Madrid and other cities to protest against job and budget cuts in public education.
Prime Minister Jose Luis Rodriguez Zapatero announced earlier this year he would not run for a third term as his approval ratings sank in tandem with employment.
The Socialists chose veteran politician Alfredo Perez Rubalcaba as their leader for the campaign, but he has struggled to differentiate himself from Mr Zapatero, since he served in his cabinet for years, most recently as his deputy.
Mr Rubalcaba spent the last week of the campaign trying to get out the Socialist vote, not to win, but to prevent the PP taking an absolute majority in parliament.
