Spaniards began voting on Sunday in a potentially close-run general election that could see Prime Minister Pedro Sanchez lose power since June 2018.

Voting opened at 9 a.m. (0700 GMT) and will close at 8 p.m. (1800 GMT), when exit polls will be released, as the final result is expected to be decided by fewer than a million votes and fewer than 10 seats in the 350-seat parliament.

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.

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

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

"The status quo scenario and a hung parliament are still a real possibility, likely with 50% 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 of the election could hinge on whether Feijoo or Sanchez command the support of enough smaller parties to form a coalition government.

The prime minister's minority Socialist government is currently in coalition with far-left Unidas Podemos which is running in Sunday's election under the Sumar platform.

Access24 reports that Prime Minister Sanchez, who has been in office since 2018, saw his term as prime minister marked by crisis management - from the COVID pandemic and its economic effects to the politically disruptive consequences of the failed 2017 independence bid in Catalonia.

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