Mathieu Klein (born 20 January 1976) is a French politician serving as Mayor of Nancy since 2020. A member of the Socialist Party since 1992, he is also President of the Departmental Council of Meurthe-et-Moselle. After the 2020 French municipal elections, he became the first socialist Mayor of Nancy since the end of the second World War. Early life and education Mathieu Klein was born into a family of teachers in Phalsbourg, Moselle. Alongside his two brothers, he was brought up in Holving, before pursuing his secondary education at Sarreguemines. He moved to Nancy, France in 1993 to study history and sociology. He then continued his university studies in Paris. Political career Mathieu Klein is a member of the Socialist Party since 1992 and his support in favour of a positive result in the French referendum on the Maastricht Treaty. He then became a student member of the National Union of Students of France in Nancy, then Paris becoming a member of its national bureau in charge of health matters. In 1994 in Nancy he founded an LGBT association dedicated to the promotion of equality and fighting against homophobia. He pursued his political career within the Socialist Party, becoming Departmental President of the Young Socialist Movement, Secretary of the Nancy branch of the Socialist Party and then, in 2008, First Secretary of Meurthe-et-Moselle branch of the party and member of its national bureau. In 2000 he worked under the then President of the Departmental Council of Meurthe-et-Moselle, the socialist Michel Dinet, who would go on to become his political mentor. In the 2004 French departmental elections, Klein was elected Departmental Councillor of Meurthe-et-Moselle in the Nancy North constituency, winning against Senator Philippe Nachbar, a member of the UMP, in the second round with 60.7% of the vote. In the 2011 elections, Klein was reelected with 61.66% of the vote in the second round. Following the 2002 French presidential election, he joined the New Socialist Party. In 2009, he joined the team of Martine Aubry, the then First Secretary of the Socialist Party, accompanying her candidacy in the 2011 French Socialist Party presidential primary. In 2005, Klein contested a by-election in Meurthe-et-Moselle's 1st constituency, but was defeated by 399 votes by the incumbent Laurent Hénart. In the 2007 French legislative election, Klein stood as a candidate again and lost, obtaining 49.2% of the vote in the second round. In the 2014