Sen. Bill Cassidy faces a tough situation as he prepares to question Robert F. Kennedy Jr. in two Senate hearings. Cassidy, a strong vaccine advocate, previously supported Kennedy’s confirmation as health secretary but has clashed with him over vaccine policies. Kennedy, a longtime anti-vaccine activist before entering politics, has moved to dramatically scale back vaccine guidance in his time in the Trump administration. The hearings on Wednesday will be the first time Cassidy questions Kennedy publicly since September, and it comes as Cassidy faces a competitive primary election in his home state of Louisiana in less than a month.