Mathieu Klein is a member of the
Socialist Party since 1992, and has 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, and then in
Paris, he became 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. Mathieu Klein pursued his political career within the Socialist Party, ascending to become the Departmental President of the
Young Socialist Movement, Secretary of the Nancy branch of the Socialist Party, and then, in 2008, assuming the role of First Secretary of the Meurthe-et-Moselle branch of the party, alongside being a member of its national bureau. In 2000, he worked under Michel Dinet who was the then President of the Departmental Council of the Meurthe-et-Moselle and also the socialist, who would go on to become his political mentor. In the
2004 French departmental elections, Klein was elected as the Departmental Councillor of the 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 re-elected 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 French municipal elections in Nancy, Klein's list was defeated by
Laurent Hénart. Following the accidental death of his mentor Michel Dinet, he replaced him as President of the Departmental Assembly of Meurthe-et-Moselle in 2014, leaving his position as Departmental Vice-President for education and civic innovation on the Departmental Council. In the
2015 French departmental elections, Klein was elected in the Nancy 2 canton, receiving 56.7% of the vote, and returned as President of the Departmental Council. In 2016, Klein announced his support for
Manuel Valls and became one of his spokespersons during the
2017 French Socialist Party presidential primary campaign. Following the proposal of
French Prime Minister Édouard Philippe in 2018, Mathieu Klein was made responsible for a project on the professional integration of beneficiaries of the French welfare benefit
Revenu de solidarité active with
Claire Pitollat. In October 2018, Klein refused a ministerial position in
Second Philippe government. In the
2020 French municipal elections in Nancy, Klein headed the
Nancy en grand list of the Socialist Party, which took its First place in the First round on 15 March 2020, with 37.9% of the vote. Following this result, Klein merged his list with that of
Europe Ecology – The Greens. In the Second round, held on 28 June 2020, Klein prevailed with 54.5% of the vote. He was confirmed as
Mayor on 15 July 2020 by 43 votes in the
municipal council of Nancy, becoming the first
left-wing person to exercise this mandate since the end of the Second World War. He is seconded by twenty
adjoints au maire. == Personal life ==