In an extraordinarily tense showdown on Thursday, senators of both parties confronted Health Secretary Robert F. Kennedy Jr. over his vaccine policies, his firing of the director of the C.D.C., and the growing list of federal health officials who have resigned in protest of his leadership.
Sheryl Gay Stolberg, who covers health policy for The Times, explains what it was like in the room and describes what seems like a turning point in the relationship between Congress and Mr. Kennedy.
