Robert F. Kennedy Jr. 's bid to be the nation's top health official is uncertain after a key Republican joined Democrats to raise persistent concerns over the nominee's deep skepticism of routine childhood vaccinations that prevent deadly diseases.

Kennedy Jr. "go wild" on health, food and medicine as head of the Department of Health and Human Services. Kennedy, a Democrat who ended up supporting Trump in the 2024 presidential campaign, now faces two separate confirmation grillings over his controversial views -- on everything from vaccines to abortion -- that have both Republicans and Democrats raising concerns.

During his Senate confirmation hearing, Kennedy claimed he is not against vaccination, contrary to decades of public comments.