Stefanos Kasselakis, the leader of Greece's main opposition, the Syriza party, has stepped down and announced the creation of a new political movement.

The Greek shipping investor and former banker, who burst into Greek politics more than a year ago, is leaving the left-wing party to form his own, as yet unnamed, organization.

His departure follows a contentious two-day party congress, where the central committee blocked his candidacy for upcoming leadership elections on Nov 24, prompting him to announce a fresh democratic platform.

Denied entry to Syriza's congress in Athens on Friday, Kasselakis responded by convening supporters at his office on Saturday, where he unveiled his plans, reported Euronews.

"Today, a movement is being created, a movement of democracy and free citizens. I will talk about the name in a few minutes. Yesterday, we had a dilemma. The dilemma was do we legitimize the process and by our silence make it right or do we speak out? Because indeed silence is not guilt, it is complicity," he said.

Later, he added: "You will decide what to call this movement. You will be the owners and its president will be your servant."

Multiple Syriza lawmakers have pledged to leave the party and become independents in the wake of Kasselakis' exit, effectively making the center-left Pasok party Greece's primary opposition force, reported The Guardian newspaper.

After spending most of his life in the United States, the 36-year-old Kasselakis made his Greek political debut in May 2023. He took over Syriza's leadership in September 2023 following the party's double electoral defeat that summer and the departure of veteran leader Alexis Tsipras.

The once-dominant Syriza, which lost power in 2019, was crushed in last year's election when New Democracy, led by Prime Minister Kyriakos Mitsotakis, won decisively.

Syriza then faced a major split when dozens of members left to form the New Left party last November, with party tensions deepening further after poor results in June's European Parliamentary elections.

Addressing supporters outside his new headquarters, Kasselakis declared that "Syriza has closed its democratic chapter" and he positioned himself as leader of a new progressive force, reported the Politico news website.

"Today is a joyful day because a movement of democracy, free citizens, and progress is being created," he said. "We are creating a movement from society, for society."

Kasselakis said the new party is "the continuation of the democratic Syriza party, not the one that is now blocking people from taking part in the processes of the party".

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