LISBON, May 30, 2025 (BSS/AFP) - Centre-right leader Luis Montenegro returned as Portugal's prime minister on Thursday but will have to form an alliance or lead a minority government after an inconclusive snap election.

His appointment by President Marcelo Rebelo de Sousa came a day after the final vote count showed the far-right Chega party took second place in the May 18 election, posing an early challenge for Montenegro, who has ruled out working with them.

Montenegro ruled out a "permanent governance agreement", but said he would be speaking with "all political parties".

"The government is going to continue its work," he said in a statement on his website.

Chega's name means "enough" and it has benefited from the protest vote in Portugal. Its founder and leader Andre Ventura has called on Montenegro to "break" with the other main party, the Socialists, saying Chega's performance "marks a profound change in the Portuguese political system".

Montenegro's Social Democratic Party is the main component of the Democratic Alliance, which secured 91 seats in the election -- but fell short of the 116 needed for a majority.

"Having ensured the possibility of parliamentary support for the new government, the president today appointed Mr Luis Montenegro as prime minister," Rebelo de Sousa's office announced in a statement.

The president had held extensive talks with Portugal's main political parties ahead of his announcement.

He had said he wanted to ensure the government would be stable, after three parliamentary elections in three years in the southern European country.

- 'Responsible opposition' -

Ventura has vowed to lead a "responsible opposition", saying no one wants "a new crisis".

The election was called after Montenegro, a 52-year-old lawyer, lost a vote of confidence in parliament following accusations of conflicts of interest involving a family company.

The vote shifted Portugal firmly to the right, with the Socialists reduced to the third party in parliament, with 58 seats.

The Socialists' secretary general Pedro Nuno Santos resigned after the party's poor showing .

The politician tipped to succeed him, Jose Luis Carneiro, said Thursday the party "will have a constructive attitude" toward the next government.

Support for Chega has grown in every election since the party was founded in 2019 by Ventura, a former trainee priest who later became a television football commentator.

It won 1.3 percent of the vote in an election the year it was founded, giving it a seat in parliament -- the first time a far-right party was in Portugal's legislature since a 1974 coup toppled a decades-long rightist dictatorship.

Chega became the third-largest force in parliament in the 2022 general election and quadrupled its parliamentary seats last year to 50, mirroring gains by similar parties across Europe.