WASHINGTON (NEXSTAR) – Sen. Bernie Sanders (I-Vt.) was one of many senators to question President Donald Trump’s pick for Health and Human Services Secretary, Robert F. Kennedy Jr., during a Senate confirmation hearing on Wednesday.

Sen. Sanders used his time to press RFK Jr. on what he called a sudden change in his stance on abortion.

“I have never seen any major politician flip on that issue quite as quickly as you did when Trump asked you to become HHS secretary,” Sen. Sanders said. “Tell me why you think people should have confidence in your consistency and in your word?”

Kennedy responded to Sen. Sanders saying he believes “every abortion is a tragedy.”

Kennedy has previously made comments supporting abortion rights. He faced backlash from Democrats throughout Wednesday’s hearing for saying he would support President Trump’s anti-abortion policies.

Sen. Sanders also grilled Kennedy about his views on vaccines. Sanders showed images of baby onesies he says are sold by the Children’s Health Defense, which is an anti-vaccine group founded by Kennedy.

The onesies pictured read “Unvaxxed Unafraid” and “No Vax No Problem.”

“You’re coming before this committee and you say you’re pro-vaccine,” Sanders said. “Yet your organization is making money selling a child’s product to parents for $26 which casts fundamental doubt on the usefulness of vaccines.”

Kennedy responded, saying he resigned from the organization and therefore no longer has any control over it. He said several times on Wednesday that he is “supportive of vaccines.”

Kennedy insists that he is not anti-vaccine despite his record over the years of promoting anti-vaccine views.

Wednesday’s confirmation hearing before the Senate Finance Committee is the first of two confirmation hearings for Kennedy.