The hearings went awry many times, and Democrats worry thathe doesn’t understand the U.S. medical system at all.

The U.S. Senate voted Thursday to confirm Robert F. Kennedy Jr. as secretary of the Department of Health and Human Services (HHS), a victory for President Trump. Kennedy has come under intense scrutiny for his controversial views on vaccines and public health policy.

The Senate confirmed him in a largely party-line vote of 52-48. However, Kentucky Republican Sen. Mitch McConnell once again joined Democrats in opposing the nomination. So far, McConnell has voted against Trump's cabinet nominees three times, more than any other Republican senator.

The confirmation vote underscored Trump's influence over the Senate's Republican majority, which managed to win approval even as some nominees faced questions about their ability to be confirmed. Those confirmed by Senate Republicans to top government positions include John F. Kennedy (health secretary), Pete Hegseth (defense secretary) and Tulsi Gabbard (director of national intelligence).

McConnell also previously opposed the nominations of Hegseth and Gabbard. His position in the Republican Party has undergone changes, gradually transforming from the leader of the party's establishment to a key swing vote. McConnell has long had a tense relationship with Trump and other members of the MAGA faction, in part because of his opposition to the Republican Party's increasingly isolationist tendencies.

In a statement, McConnell explained his reasons for opposing Kennedy's nomination, citing his own experience with polio as a child.

"This administration, led by the same president who created the medical miracles with Operation Warp Speed (OWS), should have a leader who is willing to unreservedly acknowledge the effectiveness of life-saving vaccines and understands the fundamentals of the U.S. health care system. Kennedy has failed to prove that he is the best person to lead the nation's largest health agency," McConnell said.

Kennedy will now serve as one of the nation's most important public health officials.

The U.S. Department of Health and Human Services is comprised of many major federal health agencies, including the Food and Drug Administration, the National Institutes of Health, the Centers for Medicare and Medicaid Services, and the Centers for Disease Control and Prevention.

During his congressional confirmation hearing, Kennedy denied being an anti-vaxxer and told senators he supported "pro-safety". "I believe vaccines play a vital role in health care," he said.

During the hearing, Vermont independent Sen. Bernie Sanders asked Kennedy if he agreed with existing evidence that vaccines do not cause autism, citing dozens of studies. Kennedy began by saying, "If you showed me these studies, I would absolutely..." before he finished speaking, Sanders interrupted: "That is a very disturbing answer because these studies are already here. As a candidate for this position, your job is to have studied this information."

This is not the first time Kennedy has claimed that he is not an "anti-vaccine" person, but a CNN fact check in 2023 pointed out that despite his statement, Kennedy has long been one of the most well-known anti-vaccine activists in the United States and has used false and misleading information for years to erode public trust in the safety of vaccines.

Routine childhood vaccinations are expected to prevent hundreds of millions of illnesses, tens of millions of hospitalizations and more than 1 million deaths among people born between 1994 and 2023, according to the Centers for Disease Control and Prevention. Vaccines undergo rigorous testing before release and their safety is continuously monitored.

During his confirmation hearing, Kennedy made several errors in describing the operations of Medicare and Medicaid, deepening concerns among Democrats about his ability to lead the massive agency. As Surgeon General, he will oversee the two programs that provide health insurance to more than 150 million Americans.

At one point, Kennedy mistakenly described Medicare Part A as "primarily for primary care or physicians," when in fact it covered hospitalization. He also ignored that half of Medicare enrollees are enrolled in Medicare Advantage plans administered by private insurance companies that provide care to beneficiaries through government funding. Additionally, he incorrectly stated that Medicare is paid for by employer taxes, but he left out other sources of funding, such as enrollee premiums and government support.

When describing Medicaid, Kennedy said the program is funded entirely by the federal government, however it is actually jointly funded by the federal government and states. He also noted that Medicaid costs are too high, but states only charge nominal out-of-pocket payments (copays) for certain services.

Kennedy began his presidential campaign during the 2024 election, initially as a Democratic challenger to then-President Joe Biden and later as an independent candidate. His campaign focused on reversing the "chronic disease epidemic" and proposed policies aimed at reforming food safety and environmental guidelines, promoting holistic medicine and restructuring public funding for vaccine research.

In the final stages of the campaign, Kennedy met with Trump several times to discuss the possibility of supporting Trump in exchange for a position in the Trump administration. Eventually, Kennedy dropped out of the race and endorsed Trump.

The votes to confirm Kennedy, Gabbard and Hegseth showed the extent to which the Trump administration was able to keep Republican senators aligned throughout the confirmation process, minimizing dissent as the administration attempts to enact historic reforms to the federal government.

Ultimately, the White House won over skeptical Republican senators through Trump's private conversations, Vice President Vance's extensive involvement, and the nominees' assurances that their past controversial views would not impact their positions in Trump's Cabinet.

Multiple sources familiar with the strategy told CNN that those closest to Trump have long believed that successfully pushing his nominees through the confirmation process would be a critical early test of his strength in Congress.

Louisiana Republican Senator Bill Cassidy, a physician, has said he "struggled" with Kennedy's nomination. But Cassidy later announced he would vote in favor, saying he had "intensive conversations" with the White House and thanked Vice President Vance for his "honest advice."

Sen. Lisa Murkowski, R-Alaska, said on Wednesday that she would support Kennedy's confirmation.

"I continue to have concerns about Kennedy's views on vaccines and his selective interpretation of scientific research, which is why I initially had concerns about his nomination," Murkowski said. But she went on to say that Kennedy "made multiple commitments to me and my colleagues" and that "he committed to working with Congress to ensure that the public has access to information and that vaccine recommendations are made based on data-driven, evidence-based and medically sound research."