Spaniards are voting in a potentially close-run general election that could see Prime Minister Pedro Sanchez’s governing Socialists lose power and a far-right party make up part of the government for the first time in 50 years.

Voting opened at 9am (0700 GMT) on Sunday and will close at 8pm (1800 GMT) when exit polls will be released.

The final result is expected to be decided by fewer than a million votes and fewer than 10 seats in the 350-seat parliament, experts say.

Mr Sanchez called the election early after the left took a drubbing in local elections in May but his gamble to wrong-foot his opponents could backfire.

Opinion polls show the election will likely produce a win for Alberto Nunez Feijoo’s centre-right People’s Party, but to form a government it will need to partner with Santiago Abascal’s far-right Vox.

This would be the first time a far-right party entered government since Francisco Franco’s dictatorship ended in the 1970s.

Many Spaniards are furious at being called out to vote at the height of the sweltering summer when they are on holiday.

The postal service said on Saturday postal votes had set an all-time record of 2.47 million, as many people cast their ballot from the beach or mountains.

“The status quo scenario and a hung parliament are still a real possibility, likely with 50 per cent combined odds in our view,” Barclays wrote in a recent note to clients, citing the thin margin in PP’s favour and overall uncertainty regarding polling and voter turnout.

The outcome could hinge on whether Mr Feijoo or Mr Sanchez command the support of enough smaller parties to form a coalition government.

The prime minister’s minority Socialist (PSOE) government is currently in coalition with far-left Unidas Podemos that is running in Sunday’s election under the Sumar platform.

It has passed progressive laws on euthanasia, transgender rights, abortion and animal rights and has told voters such rights could be stripped back if the anti-feminist, family values-focused Vox is part of the next government.

Mr Sanchez, in office since 2018, has seen his term as prime minister marked by crisis management – from the COVID-19 pandemic and its economic effects to the politically disruptive consequences of the failed 2017 independence bid in Catalonia.

PP leader Feijoo, who has never lost an election in his native Galicia, has played on his reputation for dullness, selling himself as a stable and safe pair of hands, which could appeal to some voters, experts say.

The formation of a new government depends on complex negotiations that could take weeks or months and might even end in fresh elections.

Such uncertainty could dent Madrid’s effectiveness as the current host of the six-month rotating presidency of the European Union Council as well as its spending of EU COVID recovery funds.

-Reuters