Following a tense exchange with Robert F. Kennedy Jr. during a Senate hearing on Thursday, U.S. Sen. Michael Bennet, a Colorado Democrat, reiterated his call for the Health and Human Services secretary’s ouster, charging that the Trump cabinet member’s tenure has been “catastrophic” for the country’s health care system.

The two clashed nearly continuously throughout the lawmaker’s allotted five minutes of questioning at a hearing before the U.S. Senate Finance Committee in Washington, with Bennet repeatedly pressing Kennedy on the federal department’s policies toward vaccines.

“This is about fighting for American kids, American parents and American families, who are getting complete disinformation on vaccines from Donald Trump’s secretary of (Health) and Human Services,” Bennet said in a video posted to social media after the hearing. “We need to let them know that we will not stand for this in America.”

During the roughly three-hour hearing, Bennet charged that Kennedy recently replaced every member of a Center for Disease Control and Prevention vaccine advisory panel with “people with ideas that are completely outside the mainstream,” to which Kennedy interjected, “You mean, outside of the pharmaceutical paradigm?”

Benne said he is concerned that the panel, set to meet later this month, could restrict access to routine childhood vaccines, including those for Hepatitis B, measles, mumps and rubella.

“These are common back-to-school vaccinations for children all over the industrial world,” said Bennet, who served as superintendent of Denver Public Schools before his appointment to the U.S. Senate and is running for governor in Colorado. “If you change that, you owe parents in Colorado and across the country the benefit of some transparency.”

Kennedy denied that fewer children would be able to receive what Bennet characterized as “common vaccinations.” Colorado’s senator sounded skeptical. Speaking over each other, the two argued about whether the vaccines in question would be “free and accessible to parents” after the CDC panel issues its recommendations, with Kennedy concluding, “I assume they will be.”

“I will hold you to that, Secretary Kennedy,” Bennet said. “Because this is not a podcast. It is the American people’s health that is on the line here.”

Asked by Bennet to guarantee that the evidence used by the vaccine panel to formulate its recommendations will be available to the public in advance of its meeting, Kennedy shot back, “All the evidence is transparent for the first time in history.”

He then asked Bennet why the lawmaker hadn’t raised the same objection when “the pharmaceutical companies were picking these people and then running their products through with no safeguards,” followed by asking Bennet why he was “evading the question.”

“I’m asking the questions here,” Bennet said multiple times, attempting to speak over Kennedy, who continued talking.

After Bennet concluded that parents and schools across the country “deserve so much better than your leadership,” Kennedy responded: “Senator, they deserve the truth, and that’s what we’re going to give them, for the first time in the history of that agency.”

The heated exchange echoed Bennet and Kennedy’s confrontation during the Trump appointee’s confirmation hearing in January, when Bennet pressed the nominee over statements he’d made about vaccine safety, pesticides and infectious diseases, including COVID-19 and AIDS.

Kennedy took heat from Democrats and Republicans alike during Thursday’s hearing, which took place a week after Trump-appointed CDC Director Susan Monarez said she was fired because of disagreements with Kennedy over vaccines and public health policy.

In a Wall Street Journal op-ed published Thursday, Monarez said she disagreed with Kennedy’s demand that she approve in advance recommendations by the department’s vaccine advisory panel, which she wrote had been “newly filled with people who have publicly expressed antivaccine rhetoric.”

Several top doctors resigned from the CDC in protest after her firing.

Kennedy disputed Monarez’s account during the hearing, saying she told him “no” when he asked if she was a “trustworthy person.” Hours later, Monarez said she stood by what she wrote and “would repeat it all under oath.”

Prior to the hearing, 11 of the 12 Democratic members of the committee — including Bennet — released a statement calling for Kennedy’s resignation, saying that their opposition to his nomination had been borne out by his performance on the job.

“Robert Kennedy must resign, and if he doesn’t, Trump should fire him before more American families are hurt by his reckless disregard for science and the truth,” the senators wrote.

Kennedy, who ran for president last cycle as a Democrat and an independent before endorsing Trump, has said that multiple shakeups at the CDC have been necessary to restore the country’s leadership in fighting infectious disease.