Trump critic Sen. Bill Cassidy (R-LA) on Wednesday pressed the president's nominee to lead the Centers for Disease Control and Prevention, asking if she would stand up to Health Secretary Robert F. Kennedy Jr., Politico reported.Erica Schwartz, if nominated, would work under Kennedy, who previously fired Susan Monarez for pushing back on the Trump cabinet member's vaccine agenda, according to Politico. Schwartz apparently struggled to convince the senators that she would push back against Kennedy during the Senate committee for her confirmation."I feel like I’m having to go after this question a little bit more firmly than I feel like I should," Cassidy told Schwartz. "You can be CDC director and just take orders. We need a CDC director who will actually stand up to crazy, stupid things being said that undermine faith in immunization."Cassidy, a physician who lost his primary to a Trump-backed challenger, has become more vocal in criticizing the administration. "I’m here personally liking you, but feeling as if I’m having to represent the public health of the United States of America, so that it’s not taken over by people who are ideologically inclined and looking to file a lawsuit, not looking to prevent disease," Cassidy said.CNN anchor Dana Bash commented on Cassidy's comments."We haven't seen him in a while; he's clearly fed up with the vaccine decisions being made by Kennedy," she said.Schwartz's response to Cassidy in the hearing did not satisfy the lawmaker's questions.CNN medical correspondent Meg Tirrell described his reactions to Kennedy's leadership around vaccines."We also heard from Cassidy at the end of the hearing just how frustrated he is with some of the vaccine language out there, including from the other nominee," Tirrell added.