Burger worked as political advisor for Minister of Social Affairs Jan van den Tempel from February 1943 until August 1943.

Burger was appointed as Minister for Return Policy in the Gerbrandy II cabinet by Queen Wilhelmina, taking office on 11 August 1943.

On 27 January 1945 Burger was forced to resign by Prime Minister Pieter Sjoerds Gerbrandy following an impromptu remark during a radio address where he differentiated between "wrongful" Dutch civilians (foute Nederlanders) and Dutch civilians who made a mistake (Nederlanders die een fout hebben gemaakt) during the War, but because Gerbrandy did not discuss this with rest of the cabinet all Social Democratic Workers' Party cabinet members resigned in response and the cabinet continued to serve in a demissionary capacity.

After the 1952 general election, Donker was appointed as Minister of Justice in the Drees II cabinet and the Labour Party leadership approached Burger as parliamentary leader, taking office on 2 September 1952.

On 11 December 1958 the Drees III cabinet fell and incumbent Prime Minister and Leader of the Labour Party Drees announced his retirement from national politics and stated that he would not stand for the 1959 general election, the Labour Party leadership approached Burger as his successor, Burger accepted and became the Leader and one of the lead candidates, taking office on 22 December 1958.