AMNA NAWAZ: Meanwhile, on Capitol Hill, one of President Trump's most consequential and controversial nominees made his case for the top job at the Department of Health and Human Services.

GEOFF BENNETT: In his first of two hearings, former environmental lawyer and presidential candidate Robert F. Kennedy Jr. took tough questions from some senators, as he also faces blistering criticism from his own family.

Here's Lisa Desjardins.

MAN: We love you!

LISA DESJARDINS: Robert F. Kennedy Jr., President Trump's pick to lead the Department of Health and Human Services, greeted with applause and fanfare.

He described his mission and concern about America's chronic health failures.

ROBERT F. KENNEDY JR., Health and Human Services Secretary Nominee: Today, Americans' overall health is in grievous condition.

Over 70 percent of adults and a third of children are overweight or obese.

LISA DESJARDINS: Kennedy has won supporters in part by railing against processed food and the pharmaceutical industry as health catastrophes.

But he has also sparked concern, evident by rows of doctors and nurses in the room to oppose him.

He addressed his controversial record on vaccines before loud protests interrupted him.

ROBERT F. KENNEDY: News reports have claimed that I am anti-vaccine or anti-industry.

I am neither.

I am pro-safety.

LISA DESJARDINS: It's a change from his past words and tone.

ROBERT F. KENNEDY: They poisoned an entire generation of American children.

LISA DESJARDINS: Kennedy has a long history of vaccine skepticism.

The Washington Post found dozens of disparaging statements, including about routine childhood vaccinations, like for measles, mumps and rubella, at times wrongly claiming that vaccines cause autism.

ROBERT F. KENNEDY: What is the cure for measles?

The treatment for measles, it's chicken soup and vitamin A.

All of my kids are vaccinated.

LISA DESJARDINS: Today, Kennedy put his views this way: ROBERT F. KENNEDY: I will do nothing as HHS secretary that make it difficult or discourages people from taking any of those vaccines.

In my advocacy, I have often disturbed the status quo by asking uncomfortable questions.

Well, I'm not going to apologize for that.

LISA DESJARDINS: But Democrats railed against him as someone with dangerous health theories.

SEN. MICHAEL BENNET (D-CO): Did you say Lyme disease is a highly likely militarily engineered bioweapon?

ROBERT F. KENNEDY: I probably did say that.

LISA DESJARDINS: And as someone they say is posturing to get the job.

SEN. MICHAEL BENNET: It doesn't matter what you come here and say that isn't true.

Unlike other jobs we're confirming around this place, this is a job where it is life and death.

LISA DESJARDINS: His first of two days of testimony.

Today's is the more important.

The Senate Finance Committee is the only one that will vote on his confirmation to oversee one of the largest budgets in the U.S. government, including Medicare, Medicaid, the Food and Drug Administration, and the Centers for Disease Control.

Republicans largely asked friendly questions and defended President Trump's nominee.

SEN. STEVE DAINES (R-MT): We believe in science.

I'm thankful that you do too.

LISA DESJARDINS: But Democrats hoped to crack that unity by pointing to his past support of abortion rights.

SEN. BERNIE SANDERS (I-VT): 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.

LISA DESJARDINS: Republican Senator Steve Daines asked if Kennedy might try to limit pills, mifepristone, used for early pregnancy abortions.

ROBERT F. KENNEDY: President Trump has asked me to study the safety of mifepristone.

He has not yet taken a stand on how to regulate it.

LISA DESJARDINS: But Democrats fired back.

SEN. MAGGIE HASSAN (D-NH): Here are the safety studies that tell us mifepristone is safe and effective.

LISA DESJARDINS: Kennedy ultimately suggested more pilot programs.

Not in the room, but part of the nomination fight has been Kennedy's cousin Caroline Kennedy, daughter of former President John F. Kennedy.

In a scathing letter and video recording previously, she urged senators to reject his nomination.

CAROLINE KENNEDY, Daughter of John F. Kennedy: Bobby himself is a predator.

LISA DESJARDINS: Kennedy accused RFK Jr. of being an exploiter.

CAROLINE KENNEDY: It's incomprehensible to me that someone who is willing to exploit their own painful family tragedies for publicity would be put in charge of America's life-and-death situations.

LISA DESJARDINS: But Republicans cast him as a nonpartisan attempting to bridge divide.

SEN. RON JOHNSON (R-WI): I thank you for that.

I truly appreciate what you're doing here.

LISA DESJARDINS: Elsewhere on Capitol Hill, two more nominees with smoother paths to confirmation, Wall Street executive and cryptocurrency backer Howard Lutnick to run the Commerce Department and former Senator Kelly Loeffler to be in charge of the Small Business Administration.

And more picks getting green lights.

Pam Bondi to be attorney general advanced through committee, a step closer to the job.

Lee Zeldin to head the Environmental Protection Agency was fully confirmed by the Senate.

For the "PBS News Hour," I'm Lisa Desjardins.