Hundseid felt forced to join Nasjonal Samling who supported the Nazis in 1940, a choice he later called "cowardly".

[5] He was editor of Eidsvold Blad 1916-1918 and combined this with working as a teacher at Eidsvoll folk high school.

[6] According to Halvdan Koht who knew Kolseid when he was young, he was initially conservative and later sympathized with the Liberal Party.

[5] He became a member of the Executive Board of the Farmer's Party in 1926 and the same year elected deputy leader under Kristoffer Høgset.

[11] When the Farmer's Party formed its first cabinet in 1931, Peder Kolstad was chosen as prime minister instead of Jens Hundseid who was seen as too controversial for the role.

[12] In April 1932, Quisling strongly attacked the Labour Party in the trontale (opening secession debate) in the Parliament.

[13] In summer 1932, diplomat Fritz Wedel Jarlsberg secretly gave authorization from Hundseid to negotiate the Eastern Greenland dispute with Denmark.

Hundseid signed a somewhat moderated statement where he declared he would become a member of Nasjonal Samling and be writing newspaper contributions in favour of NS.

[16] While Hudseid distanced himself from Nasjonal Samling and fascism after the war, he also had a track record of stark, antisemitic statements, including claims that jews were "not real Norwegians"[17] After the liberation of Norway on 8 May 1945, Hundseid was arrested the following day.

During the legal purge he was charged with five crimes:[15] Despite his record of antisemtism, some historians regard him as a mostly passive member of Nasjonal Samling.