He was an MP between 30 January 2003 and 14 December 2016. On 16 March 2012 he was elected parliamentary leader as well as party leader. He lost the Labour Party leadership election to Lodewijk Asscher in December 2016. Before his election to parliament he was CEO of a green energy company and a campaigner for Greenpeace Netherlands.
Diederik Maarten Samsom was born on 10 July 1971 in Groningen in the Netherlands. He was raised in Leeuwarden. His father worked as an internist and his mother as a physiotherapist.
Between 1983 and 1989, he attended the Stedelijk Gymnasium (Municipal Gymnasium) in Leeuwarden. There he became interested in physics, so he went on to study applied physics at Delft University of Technology. Samsom specialised in nuclear physics and became a level three radiation expert. He graduated in May 1997, obtaining a Dutch engineer's degree (Dutch: ingenieur). He was also on the board of the national students' union LSVb and edited a yearly edition of the Poenboek, a students' guide concerning monetary issues.
Samsom had been involved in environmentalism long before entering politics. Samsom joined environmental organisation Greenpeace Netherlands in September 1995 as a volunteer. He led several campaigns and projects until he quit in December 2001, when the PvdA approached him offering a career in politics. He also worked as the CEO of Echte Energie (Real Energy), a small green energy trading company, from August 2002 until January 2003.
Samsom became a member of the social democratic Labour party while a student in Delft. He left the party but rejoined in February 2001. He stood as a candidate in the 2002 Dutch general election, but he was not elected due to the PvdA losing almost half of its seats in the election. The party regained most of its seats in the 2003 election and this time Samsom was given a high position (nine) on the list of candidates. He was subsequently sworn in as a member of the House of Representatives on 30 January 2003.
Together with fellow PvdA parliamentarians Staf Depla and Jeroen Dijsselbloem he traveled around the country campaigning. They operated under the name The Red Engineers (Dutch: De rode ingenieurs), referring to both their scientific backgrounds and their red overalls. NRC editor Coen van Zwol called their campaign fresh, clear and sharp (Dutch: fris, helder en scherp).
Before being admitted as the leader of the Labour party, Samsom was the party's spokesperson on environmental issues: sustainability, climate and energy, traffic congestion and railway issues and projects. He was nineteenth on the list of candidates in the 2006 Dutch general elections and he received a high number of 6248 preference votes.
In April 2008, Samsom was a candidate for succeeding Jacques Tichelaar as fractievoorzitter, but eventually he lost the vote to Mariëtte Hamer.
Jacques Tichelaar became the leader of the parliamentary party shortly after the 2006 general election in February 2007 but fell ill in January 2008. He had to undergo a septuple bypass surgery and it took him three months to recuperate. On 16 April, he announced he had decided to resign from office for health reasons. He planned to return as a parliamentarian on 1 July 2008. As vice parliamentary leader Hamer had led the party in Tichelaar's absence. The next day she decided to run for office. Three days later, Samsom officially announced he would also compete in the race. Other names were mentioned, but only Samsom and Hamer decided to vie for the position. All 33 parliamentarians gathered two days later to discuss the position and cast their votes, resulting in a victory for Hamer.
According to pollster Maurice de Hond, a majority of the 2006 Labour voters preferred Samsom as party leader. Out of a total of 1,500 Labour voters, 26% favoured Hamer while 42% liked Samsom better. From the people who indicate they will vote for the PvdA in the future a smaller majority of 40 to 35 preferred Samsom.
On 22 February 2012, following Job Cohen's resignation as party leader, Samsom stood in the party's leadership election, which was held among the party members. On 16 March 2012, he won the election by a landslide with 54% of the vote, with the runner-up Ronald Plasterk receiving 32% of the vote. Samsom stated he would like to become prime minister, or otherwise continue his role of chairman of his party in the House of Representatives.
Polls suggest that the Labour party lost most of its electoral base while Samsom was in charge. On 9 December 2016 Samson lost the leadership of the Labour Party in an election against Lodewijk Asscher. He obtained 45,5% of the vote. Samson resigned from the House of Representatives on 14 December, and was replaced by Rien van der Velde. Attje Kuiken took over the role of group leader of the Labour Party in the House of Representatives on 12 December.
NRC Handelsblad referred to Samsom as quizking him after he won his fifth televised game show. Particularly notable are his consecutive victories in the 2005 and 2006 National IQ Tests. According to the test, he has an IQ of 136. He also won the popular National News Quiz in 2005 and 2006 and in May 2008 he was crowned winner of the Big History Quiz.
Samsom was raised in a non-religious family and considers himself an atheist. He is a non smoker and observes a vegetarian diet. He cites swimming and water polo as his favourite sports. Samsom is married and has two children. His daughter Benthe was born in 2001 and his son Fane was born in 2006. Samsom mentioned them in several political debates and interviews in a for the Netherlands unprecedented and criticized way, including drawing attention to his daughter's disability. He also involved his private life and family in his 2012 electoral campaign, most notably by featuring his two children in an official party TV ad.
Samsom lived on a houseboat in Broek in Waterland with his then girlfriend and daughter before moving to Leiden, where he still resides as of 2012. In a 2012 interview with Marie Claire Samsom admitted that before his marriage he had been unfaithful "perhaps once or twice".