Greece's Socialist PASOK becomes main opposition after leftist party collapse

Greece saw a change in its main opposition party on Thursday after a wave of defections from the leftist Syriza party opened the door for the centre-left PASOK to challenge the dominance of rightist Prime Minister Kyriakos Mitsotakis.

The opposition shift will revive a more traditional battle for the political centre that dominated Greek politics before a 2009-18 debt crisis triggered years of social and political instability.

Months of infighting and a leadership struggle have left Syriza with 29 lawmakers, two fewer than PASOK, in the 300-seat parliament.

The pivotal resignations came on Thursday when Syriza lawmaker Theodora Tzakri and another MP quit the party's parliamentary group.

As the official opposition, PASOK will assume more benefits, including more time for speakers. It will aim to use the higher profile to win back voters from Mitsotakis' New Democracy party, which won elections in 2019 and 2023 but whose support has shown signs of waning in recent opinion polls.

"Responsibility is high," PASOK spokesperson Costas Tsoukalas told Reuters, adding that an official announcement was pending. "We will meet our increased parliamentary duties. The country needs political change."

PASOK dominated Greek politics for three decades but support evaporated after 2010 when it signed up to the country's first international bailout in exchange for harsh austerity.

Syriza was catapulted to power in January 2015 on promises to end the belt-tightening but made a U-turn months later, signing up to Greece's third international bailout.

Its election defeat in 2023 prompted the resignation of leftist firebrand Alexis Tsipras, who was replaced by former Goldman Sachs associate and political novice Stefanos Kasselakis.

His corporate-style leadership drew protests from traditional leftists and lawmakers who quit the party, some of them creating a new parliamentary group. Tension peaked at a party congress, when Kasselakis resigned from Syriza, announcing the launch of his own new party.