In February bill cassidy, a Republican senator and a doctor, cast a deciding vote to confirm Robert F. Kennedy junior as the leader of America’s health department. He said he did so after Mr Kennedy, an outspoken vaccine sceptic, promised he would not interfere with an influential panel of vaccine experts at the Centres for Disease Control and Prevention (CDC). For Dr Cassidy that guarantee, among others, was pivotal. This month the alleged bargain unravelled. Mr Kennedy removed all 17 members of the panel, replacing them with a smaller group of vaccine sceptics and scientists without expertise in vaccines. On June 23rd Dr Cassidy called for the committee’s meeting this week—one of a handful of such convenings each year—to be delayed.