Dassen's transition to political life was caused by a variety of factors, including increased nationalism and populism, Brexit and the election of Donald Trump as President of the United States. Unable to find an established political party that fit him, he joined Volt Europa, who were seeking to form a Dutch wing, in February 2018 and became a volunteer. Dassen was one of the people who founded Volt Netherlands on 23 June 2018 and started serving as its treasurer. He quit his job at ABN AMRO in September to focus on politics full-time and also became Volt's secretary. Dassen succeeded Reinier van Lanschot as party chair on 15 December 2018, when Van Lanschot was chosen as the party's for the 2019 European Parliament election. Dassen himself was listed third on the Volt Netherlands party list. The party received 1.93% of the vote, not enough to meet the threshold for a seat in the European Parliament.