The election, the third in as many years, was called just one year into the minority government's term after Prime Minister Luis Montenegro failed to win a parliamentary vote of confidence in March when the opposition questioned his integrity over dealings of his family's consultancy firm.
Official electoral data showed the AD receiving over 34% of the vote.
Montenegro has refused to make any deals with Chega, meaning his government would have to negotiate piecemeal parliamentary support.
Early tallies can be unreliable as results from smaller municipalities come in first, while ballots in large cities such as Lisbon and Porto are counted towards the end.
Anti-immigration, anti-establishment Chega, a party founded in 2019 by charismatic former football commentator Andre Ventura, became the third-largest parliamentary force in 2022 and quadrupled its seats in 2024.
It could be the first time in almost 40 years that the Socialists finish below the top two.
Outside the polling station where Montenegro voted in the northern city of Espinho, Irene Medeiros, 77, said the “best candidate must win,“ but that she feared more uncertainty ahead.
“The only doubt is whether the AD will form a new minority government ... or whether it will form a post-electoral coalition with IL, even if this coalition does not guarantee an absolute majority,“ he said, referring to the pro-business Liberal Initiative (IL) party.
Shortly after casting his own ballot, Montenegro told reporters he was confident stability could be achieved.
Portugal has outperformed most European Union countries on economic growth, and run budget surpluses and reduced its debts under both centre-left and centre-right governments.
But further political instability could delay major projects such as lithium mining in the north, and potentially compromise the long-delayed privatisation of the TAP airline.
Read More Details
Finally We wish PressBee provided you with enough information of ( Portuguese PM's party claims election win, falls short of majority )
Also on site :