Born in Bártfa, Austria-Hungary (now Bardejov, Slovakia) to a Zipser family, Rajniss's surname initially reflected his German origins before he changed it to a Hungarian version.

[2] Before long he had secured funding from Nazi Germany for his political endeavours and this was to be one of his two main sources of income, the other being acting as a 'toy boy' to a number of wealthy old women.

[1] However he left this group in October 1937 to join with Zoltán Böszörmény and Fidél Pálffy in launching the United Hungarian National Socialist Party, one of a number of largely failed attempts to bring Hungary's Nazis under one umbrella.

[1] By this time Rajniss had again switched his support, this time to Ferenc Szálasi (although he never sympathized with Szálasi's ideology and considered the retired army officer as a "fanatic" and "finicking") and in 1944 he was one of the leaders of the "Nemzeti Szövetség" (National Federation) parliamentary group, which contained about 200 members of Parliament committed to continuing the war on the side of the Nazis.

[3] Rajniss played a leading role in Szálasi's rise to power and was appointed part of the three-man governing council with which the Germans replaced Miklós Horthy in 1944, alongside Károly Beregfy and Sándor Csia.