In February 2023, he succeeded Pernille Vermund as leader of the Nye Borgerlige, but was dismissed and expelled from the party in March after disputes over remuneration and campaign finances.

In May 2021, he caused a social media backlash when he compared the right to free menstrual products to having "underpants in public toilets" in case someone soils themselves, a comparison that was described as "pure nonsense" by Charlotte Wilkens, chief physician at the Department of Gynecology and Obstetrics at Hvidovre Hospital.

[8] On 10 January 2023, Pernille Vermund announced her intention to step down as leader of Nye Borgerlige, explaining her resignation with a desire to get her "life and family back".

[9] At an extraordinary national executive (hovedbestyrelse) meeting on 17 January, Boje announced his candidature for the leadership post, receiving support from most of the parliamentary group.

[18] At the same time, Vermund conveyed her willingness to once again take over as party leader[19] and to run in the next general election.

[26] On 27 February 2024, he once again suggested it, proposing that members of such a party should at most be an MP for ten years.

[34] Boje rules out supporting Mette Frederiksen as Prime Minister of Denmark, due to the mink case in 2020.