Swearing-in ceremony of new ministers at Ajuda Palace in Lisbon
Portuguese President Marcelo Rebelo de Sousa speaks during the swearing-in ceremony of Prime Minister Antonio Costa and his new government, at Ajuda Palace in Lisbon, Portugal March 30, 2022. Reuters

Portuguese President Marcelo Rebelo de Sousa will address the nation at 8 p.m. (1900 GMT) on Thursday, a spokesperson for the presidency said, after his rift with Prime Minister Antonio Costa brought the country to the verge of a political crisis.

Opposition parties on Wednesday called on the president to use his power to dissolve parliament after Costa rejected an offer by Infrastructure Minister Joao Galamba to resign in a deepening scandal around state-owned airline TAP, snubbing Rebelo de Sousa.

The conservative president, who had made clear he wanted Galamba out, said he disagreed with Costa's decision having previously warned that he could disband parliament if the government lost credibility.

Rebelo could use his address to issue another warning to Costa, or say he will summon his consultative body, the Council of State, to discuss dissolving parliament. The prospect of any snap election producing an unstable government could stay his hand, analysts say.

With high inflation and interest rates across Europe already weighing on growth this year, a government crisis would also complicate the distribution of vital EU pandemic recovery funds in Portugal.

Costa's Socialists won an outright parliamentary majority in January 2022, but his third government in a row has been plagued by problems.

More than 10 ministers and secretaries of state have left their posts in the past year, at least two of them linked to a scandal at airline TAP set off by an irregular severance payment to a board member that has snowballed to reveal what critics say are failures in government communication and decision-making.

The president offered no clues as to his plans on Wednesday evening when he walked out of his Belem Palace by the River Tagus in Lisbon to have dinner then an ice-cream in a corner shop surrounded by reporters.

"Why are you so curious? One needs to be patient... People don't need to be worried," he said.

Costa also dodged questions on Wednesday about the possibility of a full-blown crisis, saying it was "always a pleasure" to talk to the president and that his government was focussed on its daily work.

Rebelo de Sousa, a law professor, former political commentator and ex-leader of the Social Democratic Party - the main rival to the Socialists - was first elected in 2016 and won re-election in 2021 by a landslide.

In November 2021, after a hung parliament rejected Costa's budget for 2022, the president summoned his council and later dissolved parliament. Costa won a full majority in a snap election that followed.

Only once in Portugal's democratic history has a majority administration been dismissed and parliament disbanded.

In 2005, President Jorge Sampaio concluded that premier Pedro Santana Lopes' government was failing to tackle a rising deficit and economic slump and lacked overall credibility, so he used the power, often dubbed the Atomic Bomb in Portugal.

Costa, however, boasts a solid record as a deficit-buster and has achieved some of the strongest economic expansions in Europe in recent years.