Kasselakis spent a considerable portion of his life residing in the United States, where he worked in the banking and shipping sectors and contributed as a writer for The National Herald.
[5][6][7][8] The ideological shift and lack of clarity within the party led to substantial criticism of its leadership, particularly after the 2024 European Parliament elections, where Syriza’s share of the vote further dropped to 14.9%.
[14][15][16] As a result of the legal dispute the family decided to leave Greece for the USA where the eldest son, Stelios, was already studying at MIT.
[21] He was followed by his mother, who after working as a private dentist in 2006 joined the academic staff of Penn Dental Medicine as a Clinical Assistant Professor of Restorative Dentistry.
[23] In 2005—thanks to a scholarship granted by Andreas Drakopoulos [el], President of the Stavros Niarchos Foundation—he joined the Huntsman Program of the University of Pennsylvania and received two degrees: a B.S.
[24][25] In 2008, Kasselakis played an active role in the Joe Biden 2008 presidential campaign, with the main task of preparing for the ballots in every county in Iowa.
Kasselakis rebranded the family business, changing its name to "Philadelphia Coatings" in honour of the city where he had lived during college, and, according to him, increased its turnover.
In 2012, during the Greek economic crisis, he criticized the number of public sector layoffs handled by then-minister Kyriakos Mitsotakis as very low and supported the reduction of the minimum wage.
[37][38] In 2023, Kasselakis stated that from 2012 he "had developed an excellent rapport with Kyriakos Mitsotakis" and that he "penned an endorsement for him in the National Herald while he was competing for the party leadership" and still has "a lot of respect for him personally".
This is how he met the party leader, who decided to include him on the 9th (non-electoral) in the legislative election of both May and June 2023, in order to form a "triad of excellence" of members of expatriate Hellenism.
[4] After winning the election, Kasselakis expressed the desire to emulate the U.S. Democratic Party and move to the centre-left[47] arguing that Syriza must represent the patriotic left.
[48] From the beginning of his tenure, Kasselakis' leadership has faced extensive criticism, particularly from left-leaning factions within Syriza, notably the Umbrella group led by former Minister of Finance Euclid Tsakalotos.
[51] On 23 November 2023, a significant development occurred as nine MPs, one MEP, and 57 central committee members declared their departure from Syriza in protest of Kasselakis' leadership.
[53] Journalists and politicians have proclaimed this series of resignations as the end of Syriza in its present form, attributing it to a schism initiated by Kasselakis in his role as the new party leader.
[6][54][55][51][5] On 15 March 2024, Kasselakis temporarily suspended his political activities to undertake his mandatory military service for about three weeks at an artillery training camp near Thebes.
[57] Later in 2024, further criticism of his leadership arose due to the party's poor performance in the European elections, prompting several MPs and members of the political committee to demand explanations.
[58] By September 2024, the party faced another internal crisis after Kasselakis suspended two MPs, Athina Linou[59] and Pavlos Polakis, who had been embroiled in a conflict.
Polakis led a rebellion, calling for a leadership change, and by 7 September, this demand had gained significant traction among party members and MPs.
Olga Gerovasili emerged as a potential candidate,[68] while former prime minister Alexis Tsipras issued a statement openly criticizing Stefanos Kasselakis.
[77] Kasselakis is the first openly gay leader of a major political party in Greece, and supported the legalization of same-sex marriage in the country by the Hellenic Parliament in February 2024.
[56] In October 2023, controversy erupted when the Greek newspaper Estia published an article claiming that New York voter records indicated that Kasselakis was a registered member of the conservative Republican Party in the US.