[1][2] After his military service, Gruenhagen enrolled at North Hennepin Community College and then the University of Minnesota, where he majored in business.
[4] In 2022, Gruenhagen defeated Democratic nominee Chad Tschimperle 70%-30% to win a seat in the Minnesota Senate, representing District 17.
He then introduced Kevin Petersen, who Gruenhagen claimed was a friend who had "left the gay lifestyle" after ten years, entered a heterosexual marriage and fathered three children.
[12] Gruenhagen and several other Minnesota state lawmakers then attended the "Storm the Capitol" rally in St. Paul on January 6, 2021, and were later investigated for their participation in the event.
[13] On January 5, 2023, Gruenhagen and other Republican state lawmakers spoke at a rally opposing the COVID-19 vaccine and workplace mandates requiring employees to receive it.
[15] Later that month, Gruenhagen introduced Senate File 517, a bill that would require school districts to "provide instruction to students in grades 9 to 12 exploring the contrast between the scientific facts on how sickness, disease, pain, suffering, and death relate to the existence of complex living organisms, and how sickness, disease, pain, suffering, and death are a consequence imposed by the Creator of complex living organisms.