The numerous executive orders directed at transgender youth in the weeks following the 2025 U.S. presidential inauguration were likely a signal to these youth-and their parents-that the federal government no longer supported them. Using a longitudinal design spanning 3 years prior to the inauguration (2022-2024) and 2 months surrounding the inauguration, we tested whether the mental health and well-being of U.S.-based transgender youth and their parents declined relative to that of cisgender youth and their parents in a sample that, on the whole, did not support the new administration (N = 160 youth, aged 12-17 years; N = 167 parents). Across preregistered analyses, we observed significant declines in the mental health and well-being of parents of transgender youth compared to parents of cisgender youth; we observed fewer differences over time between transgender versus cisgender youth themselves. Our findings identify an immediate potential cost of the current political environment for supportive parents of transgender youth.