 In the local elections of 2002, and again in 2006, Tremopoulos was re-elected to the Council of Thessaloniki Prefecture.In the European elections of 2004, he headed the list of candidates of Ecologist Greens for the European Parliament.In the European elections of 2009, he headed the party's list of candidates again; the party received 3.45% and Tremopoulos was elected, as the first Green MEP from Greece.