CNN host Kasie Hunt and Sen. Markwayne Mullin (R-Okla.) got into a heated debate over Robert F. Kennedy Jr.’s stances on vaccines, autism and a host of other issues that the Health and Human Services secretary defended during a congressional hearing on Thursday.

“Do you believe Kennedy is right on vaccines?” Hunt asked Mullin of the longtime vaccine skeptic during an in-studio appearance on the network.

“When you start looking at statistics … what is it … today one in 10 kids [is autistic],” Mullin said.

“But why are you linking that to vaccines?” Hunt interjected.

“I’m not, I’m saying, why wouldn’t we look at it,” the senator responded. “What’s changed?”

“We have looked at it … there have been studies, the studies show there is no connection between the MMR [measles, mumps and rubella] vaccine and autism,” the cable news host shot back.

“There are several things that go into every vaccine,” Mullin insisted. “Look at how many shots we are giving our kids.”

The debate came just hours after Kennedy defended his first eight months as the nation’s top health official, fighting with senators who pressed him on the recent upheaval at the Centers for Disease Control and Prevention (CDC) and changes to vaccine policy. 

A number of key Republicans, including Sen. Bill Cassidy (La.) questioned Kennedy about his stance on vaccines for children, and Sen. John Barrasso (R-Wyo.) who said he had become “deeply concerned” about actions Kennedy has taken has Health and Human Services Director.

But Mullin defended Kennedy during his appearance on Hunt’s show.

“What is wrong with Bobby questioning what the CDC is doing?” Mullin said. “Because it’s not working right now.”