Ehrnrooth was a right-wing and anti-communist politician and critical of President Urho Kekkonen who had friendly relations to the Soviet Union. Ehrnrooth had been upset by Kekkonen's support for the war-responsibility trials in the late 1940s. He left the Swedish People's Party soon after the party had voted for a bill that prolonged Kekkonen's presidential term by four years without an election. His new Constitutional Right Party did not gain much support, winning only one seat in the 1975 and 1983 parliamentary elections and no seats at all in 1979, 1987 and 1991 elections. Ehrnrooth returned to Swedish People's Party in the 1990s.