(CNN) — Republican Sen. Bill Cassidy once hoped to forge an alliance with Robert F. Kennedy Jr. that could revitalize Americans’ trust in public health.

But just seven months after Cassidy’s vote paved the way for Kennedy to lead the US Health and Human Services Department , their relationship has reached a breaking point.

Cassidy will lead a hearing Wednesday with fired US Centers for Disease Control and Prevention chief Susan Monarez, granting her a high-profile platform to detail the internal clashes over vaccines that prompted Kennedy to oust her just four weeks after endorsing her appointment.

The hearing represents an extraordinary departure from congressional Republicans’ typical Trump-era aim of shielding the administration from criticism — instead elevating testimony that th

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